Resist composition and method of forming resist pattern

ABSTRACT

A resist composition including a resin component (A1) having a structural unit (a01), a structural unit (a02) and a structural unit (a03) derived from compounds represented by general formulae (a01-1), (a02-1) and (a03-1), respectively (W 01  represents a polymerizable group-containing group containing no oxygen; W 02  represents a polymerizable group-containing group containing oxygen; W 03  represents a polymerizable group-containing group which may contain oxygen; Wa 01  and Wa 02     represent an aromatic hydrocarbon group; Xa 03  represents a group which forms an alicyclic hydrocarbon group together with Ya 03 ; Ra 00  represents a hydrocarbon group which may have a substituent)

TECHNICAL FIELD

The present invention relates to a resist composition and a method offorming a resist pattern.

Priority is claimed on Japanese Patent Application No. 2019-201623,filed Nov. 6, 2019, the content of which is incorporated herein byreference.

DESCRIPTION OF RELATED ART

In recent years, in the production of semiconductor elements and liquidcrystal display elements, advances in lithography techniques have led torapid progress in the field of pattern miniaturization. Typically, theseminiaturization techniques involve shortening the wavelength (increasingthe energy) of the exposure light source.

Resist materials for use with these types of exposure light sourcesrequire lithographic properties such as a high resolution capable ofreproducing patterns of minute dimensions, and a high level ofsensitivity to these types of exposure light sources.

As a resist material that satisfies these conditions, a chemicallyamplified composition is used, which includes a base material componentthat exhibits a changed solubility in a developing solution under theaction of acid and an acid-generator component that generates acid uponexposure.

In the chemically amplified resist composition, a resin having aplurality of structural units is generally used in order to improve thelithography properties and the like.

For example, Patent Literature 1 describes a resist composition or thelike that employs a specific polymer compound having high aciddissociation performance and improves reactivity with an acid.

Documents of Related Art Patent Literature

[Patent Literature 1] Japanese Unexamined Patent Application, FirstPublication No. 2019-113773

SUMMARY OF THE INVENTION

As further progress is made in lithography techniques andminiaturization of resist patterns, further improvement in theresolution of resist materials has been demanded while maintaining goodlithography properties.

However, in the conventional resist composition as described in PatentLiterature 1, the resolution was not always satisfactory in a fineregion of a resist pattern.

The present invention takes the above circumstances into consideration,with an object of providing a resist composition which exhibitsexcellent resolution, and a method of forming a resist pattern using theresist composition.

For solving the above-mentioned problems, the present invention employsthe following aspects.

Specifically, a first aspect of the present invention is a resistcomposition which generates acid upon exposure and exhibits changedsolubility in a developing solution under action of acid, and whichincludes a resin component (A1) including a structural unit (a01)derived from a compound represented by general formula (a01-1) shownbelow, a structural unit (a02) derived from a compound represented bygeneral formula (a02-1) shown below, and a structural unit (a03) derivedfrom a compound represented by general formula (a03-1) shown below.

In formula (a01-1), W⁰¹ represents a polymerizable group-containinggroup; provided that the polymerizable group-containing grouprepresented by W⁰¹ contains no oxygen atom; Wa⁰¹ represents an aromatichydrocarbon group; part or all of the hydrogen atoms of the aromatichydrocarbon group may be substituted with a substituent other that ahydroxy group; Wa⁰¹ and W⁰¹ may form a condensed ring; n01 represents 1or 2. in formula (a02-1), W⁰² represents a polymerizablegroup-containing group; provided that the polymerizable group-containinggroup represented by W⁰² contains an oxygen atom; Wa⁰² represents anaromatic hydrocarbon group; part or all of the hydrogen atoms of thearomatic hydrocarbon group may be substituted with a substituent otherthat a hydroxy group; Wa⁰² and W⁰² may form a condensed ring; n02represents 1 or 2.

In formula (a03-1), W⁰³ represents a polymerizable group-containinggroup; provided that the polymerizable group-containing grouprepresented by W⁰³ may contain an oxygen atom; Ya⁰³ represents a carbonatom; Xa⁰³ represents a group which forms an alicyclic hydrocarbon grouptogether with Ya⁰³; Ra⁰⁰ represents a hydrocarbon group which may have asubstituent.

A second aspect of the present invention is a method of forming a resistpattern, including: using a resist composition according to the firstaspect to form a resist film, exposing the resist film, and developingthe exposed resist film to form a resist pattern.

According to the present invention, there are provided a resistcomposition which exhibits excellent resolution, and a method of forminga resist pattern using the resist composition.

DETAILED DESCRIPTION OF THE INVENTION

In the present description and claims, the term “aliphatic” is arelative concept used in relation to the term “aromatic”, and defines agroup or compound that has no aromaticity.

The term “alkyl group” includes linear, branched or cyclic, monovalentsaturated hydrocarbon, unless otherwise specified. The same applies forthe alkyl group within an alkoxy group.

The term “alkylene group” includes linear, branched or cyclic, divalentsaturated hydrocarbon, unless otherwise specified.

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom. The term “structural unit” refers to amonomer unit that contributes to the formation of a polymeric compound(resin, polymer, copolymer).

The case of describing “may have a substituent” includes both of thecase where the hydrogen atom (—H) is substituted with a monovalent groupand the case where a methylene group (—CH₂—) is substituted with adivalent group.

The term “exposure” is used as a general concept that includesirradiation with any form of radiation.

The term “acid decomposable group” refers to a group in which at least apart of the bond within the structure thereof is cleaved by the actionof an acid.

Examples of acid decomposable groups which exhibit increased polarity bythe action of an acid include groups which are decomposed by the actionof an acid to form a polar group.

Examples of the polar group include a carboxy group, a hydroxy group, anamino group and a sulfo group (—SO₃H).

More specifically, as an example of an acid decomposable group, a groupin which the aforementioned polar group has been protected with an aciddissociable group (such as a group in which the hydrogen atom of theOH-containing polar group has been protected with an acid dissociablegroup) can be given.

The “acid dissociable group” refers to both (i) a group in which thebond between the acid dissociable group and the adjacent atom is cleavedby the action of acid; and (ii) a group in which one of the bonds iscleaved by the action of acid, and then a decarboxylation reactionoccurs, thereby cleaving the bond between the acid dissociable group andthe adjacent atom.

It is necessary that the acid dissociable group that constitutes theacid decomposable group is a group which exhibits a lower polarity thanthe polar group generated by the dissociation of the acid dissociablegroup. Thus, when the acid dissociable group is dissociated by theaction of acid, a polar group exhibiting a higher polarity than that ofthe acid dissociable group is generated, thereby increasing thepolarity. As a result, the polarity of the entire component (A1) isincreased. By the increase in the polarity, the solubility in an alkalideveloping solution changes, and the solubility in an alkali developingsolution is relatively increased, whereas the solubility in an organicdeveloping solution is relatively decreased.

The term “base component” refers to an organic compound capable offorming a film. The organic compound used as the base component isbroadly classified into non-polymers and polymers. In general, as anon-polymer, any of those which have a molecular weight in the range of500 to less than 4,000 is used. Hereafter, a “low molecular weightcompound” refers to a non-polymer having a molecular weight in the rangeof 500 to less than 4,000. As a polymer, any of those which have amolecular weight of 1,000 or more is generally used. Hereafter, a“resin” or a “polymer” refers to a polymer having a molecular weight of1,000 or more. As the molecular weight of the polymer, the weightaverage molecular weight in terms of the polystyrene equivalent valuedetermined by gel permeation chromatography (GPC) is used.

The expression “structural unit derived from” refers to a structuralunit which is formed by cleavage of a multiple bond between carbonatoms, e.g., an ethylenic double bond.

The acrylate ester may have the hydrogen atom bonded to the carbon atomon the α-position substituted with a substituent. The substituent(R^(αx)) that substitutes the hydrogen atom bonded to the carbon atom onthe α-position is an atom other than hydrogen or a group. Further, anacrylate ester having the hydrogen atom bonded to the carbon atom on theα-position substituted with a substituent (R^(αx)) in which thesubstituent has been substituted with a substituent containing an esterbond (e.g., an itaconic acid diester), or an acrylic acid having thehydrogen atom bonded to the carbon atom on the α-position substitutedwith a substituent (R^(αx)) in which the substituent has beensubstituted with a hydroxyalkyl group or a group in which the hydroxygroup within a hydroxyalkyl group has been modified (e.g.,α-hydroxyalkyl acrylate ester) may be mentioned as an acrylate esterhaving the hydrogen atom bonded to the carbon atom on the α-positionsubstituted with a substituent. A carbon atom on the α-position of anacrylate ester refers to the carbon atom bonded to the carbonyl group,unless specified otherwise.

Hereafter, an acrylate ester having the hydrogen atom bonded to thecarbon atom on the α-position substituted with a substituent issometimes referred to as “α-substituted acrylate ester”.

The term “derivative” is a concept including a compound in which ahydrogen atom at the α-position of the subject compound has beensubstituted with another substituent such as an alkyl group or ahalogenated alkyl group, and derivatives thereof. Examples of thederivatives include a compound in which the hydrogen atom at theα-position of the subject compound may be substituted with asubstituent, and the hydrogen atom of the hydroxy group of the targetcompound has been substituted with an organic group; and a compound inwhich the hydrogen atom at the α-position of the subject compound may besubstituted with a substituent, and a substituent other than a hydroxygroup has been bonded to the subject compound. The α-position refers tothe first carbon atom adjacent to a functional group, unless otherwisespecified.

As the substituent which substitutes the hydrogen atom on the α-positionof hydroxystyrene, the same substituents as those described above forR^(αx) may be mentioned.

In the present specification and claims, some structures represented bychemical formulae may have an asymmetric carbon, such that an enantiomeror a diastereomer may be present. In such a case, the one formularepresents all isomers. The isomers may be used individually, or in theform of a mixture.

(Resist Composition)

The resist composition according to a first aspect of the presentinvention is a resist composition which generates acid upon exposure andexhibits changed solubility in a developing solution under action ofacid, and which includes a base component (A) which exhibits changedsolubility in a developing solution under action of acid (hereafter,also referred to as “component (A)”).

When a resist film is formed using the resist composition according tothe present embodiment, and the resist film is selectively exposed, acidis generated at exposed portions of the resist film, and the solubilityof the component (A) in a developing solution is changed by the actionof the acid. On the other hand, at unexposed portions of the resistfilm, the solubility of the component (A) in a developing solution isunchanged. As a result, difference is generated between the exposedportions of the resist film and the unexposed portions of the resistfilm in terms of solubility in a developing solution.

The resist composition of the present embodiment may be either apositive resist composition or a negative resist composition.

Further, the resist composition of the present embodiment may be appliedto an alkali developing process using an alkali developing solution inthe developing treatment in the formation of a resist pattern, or asolvent developing process using a developing solution containing anorganic solvent (organic developing solution) in the developingtreatment.

That is, the resist composition of the present embodiment is preferablya resist composition which forms a positive pattern in an alkalideveloping process (i.e, a positive resist compound for alkalideveloping process) or a resist composition which forms a negativepattern in a solvent developing process (i.e., a negative type resistcomposition for solvent developing process).

<Component (A)>

In the resist composition according to the present embodiment, thecomponent (A) includes a resin component (A1) (hereafter, sometimesreferred to as “component (A1)”) which exhibits changed solubility in adeveloping solution under action of acid, and the resin component (A1)includes a structural unit (a01) derived from a compound represented bythe aforementioned general formula (a01-1), a structural unit (a02)derived from a compound represented by the aforementioned generalformula (a02-1), and a structural unit (a03) derived from a compoundrepresented by the aforementioned general formula (a03-1).

As the component (A), at least the component (A1) is used, and at leastone of another polymeric compound and a low molecular weight compoundmay be used in combination with the component (A1).

In the resist composition of the present embodiment, as the component(A), one kind of compound may be used, or two or more kinds of compoundsmay be used in combination.

—Component (A1)

The resin component (A1) includes a structural unit (a01), a structuralunit (a02) and a structural unit (a03).

<<Structural Unit (a01)>>

The structural unit (a01) is a structural unit derived from a compoundrepresented by general formula (a01-1) shown below.

In formula (a01-1), W⁰¹ represents a polymerizable group-containinggroup; provided that the polymerizable group-containing grouprepresented by W⁰¹ contains no oxygen atom; Wa⁰¹ represents an aromatichydrocarbon group; part or all of the hydrogen atoms of the aromatichydrocarbon group may be substituted with a substituent other that ahydroxy group; Wa⁰¹ and W⁰¹ may form a condensed ring; and n01represents 1 or 2.

In formula (a01-1), W⁰¹ represents a polymerizable group-containinggroup.

The “polymerizable group” for W⁰¹ is a group which can cause a compoundhaving the polymerizable group to be polymerized by radicalpolymerization or the like. Examples of the polymerizable group includea multiple bond between carbon atoms, such as an ethylenic double bond.

In the structural unit (a01), the multiple bond in the polymerizablegroup of the compound represented by the aforementioned general formula(a01-1) is cleaved to form a main chain.

Examples of the polymerizable group include a vinyl group, an allylgroup, a fluorovinyl group, a difluorovinyl group, a trifluorovinylgroup, a difluorotrifluoromethylvinyl group, a trifluoroallyl group, aperfluoroallyl group, a styryl group, a vinylnaphthyl group, afluorine-containing styryl group, a fluorine-containing vinylnaphthylgroup, a norbornyl group, a fluorine-containing norbornyl group, and asilyl group.

The polymerizable group-containing group may be a group constituted ofonly a polymerizable group, or a group constituted of a polymerizablegroup and a group other than a polymerizable group. Examples of thegroup other than a polymerizable group include a divalent hydrocarbongroup which may have a substituent, and a divalent linking groupcontaining a hetero atom (provided that oxygen is excluded). Thepolymerizable group-containing group for W⁰¹ contains no oxygen atom.

Preferable examples of W⁰¹ include a group represented by chemicalformula: C(R^(X11))(R^(X12))═C(R^(X13))—Ya^(x0)—.

In the chemical formula, R^(X11), R^(X12) and R^(X13) independentlyrepresents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms ora halogenated alkyl group having 1 to 5 carbon atoms, and Ya^(x0)represents a single bond or a divalent linking group (provided that thedivalent linking group contains no oxygen).

In the chemical formula, as the alkyl group of 1 to 5 carbon atoms forR^(X11), R^(X12) and R^(X13), a linear or branched alkyl group of 1 to 5carbon atoms is preferable, and specific examples thereof include amethyl group, an ethyl group, a propyl group, an isopropyl group, ann-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, anisopentyl group and a neopentyl group. The halogenated alkyl group of 1to 5 carbon atoms represented by R is a group in which part or all ofthe hydrogen atoms of the aforementioned alkyl group of 1 to 5 carbonatoms have been substituted with halogen atoms. As the halogen atom, afluorine atom is most preferable.

Among these examples, as R^(X11) and R^(X12) a hydrogen atom, an alkylgroup of 1 to 5 carbon atoms or a fluorinated alkyl group of 1 to 5carbon atoms is preferable, and in terms of industrial availability, ahydrogen atom or a methyl group is more preferable, and a hydrogen atomis still more preferable.

As R^(X13), a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or afluorinated alkyl group of 1 to 5 carbon atoms is preferable, and interms of industrial availability, a hydrogen atom or a methyl group ismore preferable.

In the aforementioned chemical formula, the divalent linking group forYa^(x0) is not particularly limited, and preferable examples thereofinclude a divalent hydrocarbon group which may have a substituent and adivalent linking group containing a hetero atom (excluding oxygen).

—Divalent Hydrocarbon Group which May have a Substituent:

In the case where Ya^(x0) is a divalent linking group which may have asubstituent, the hydrocarbon group may be either an aliphatichydrocarbon group or an aromatic hydrocarbon group.

—Aliphatic Hydrocarbon Group for Ya^(x0)

The “aliphatic hydrocarbon group” refers to a hydrocarbon group that hasno aromaticity. The aliphatic hydrocarbon group may be saturated orunsaturated. In general, the aliphatic hydrocarbon group is preferablysaturated. Examples of the aliphatic hydrocarbon group include a linearor branched aliphatic hydrocarbon group, and an aliphatic hydrocarbongroup containing a ring in the structure thereof can be given.

—Linear or Branched Aliphatic Hydrocarbon Group

The linear aliphatic hydrocarbon group preferably has 1 to 10 carbonatoms, more preferably 1 to 6, still more preferably 1 to 4, and mostpreferably 1 to 3.

As the linear aliphatic hydrocarbon group, a linear alkylene group ispreferable. Specific examples thereof include a methylene group [—CH₂—],an ethylene group [—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], atetramethylene group [—(CH₂)₄-] and a pentamethylene group [—(CH₂)₅—].

The branched aliphatic hydrocarbon group preferably has 2 to 10 carbonatoms, more preferably 3 to 6, still more preferably 3 or 4, and mostpreferably 3.

As the branched aliphatic hydrocarbon group, branched alkylene groupsare preferred, and specific examples include various alkylalkylenegroups, including alkylmethylene groups such as —CH(CH₃)—, —CH(CH₂CH₃)—,—C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)—, and —C(CH₂CH₃)₂—;alkylethylene groups such as —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—,—C(CH₃)₂CH₂—, —CH(CH₂CH₃)CH₂—, and —C(CH₂CH₃)₂—CH₂—; alkyltrimethylenegroups such as —CH(CH₃)CH₂CH₂—, and —CH₂CH(CH₃)CH₂—; andalkyltetramethylene groups such as —CH(CH₃)CH₂CH₂CH₂—, and—CH₂CH(CH₃)CH₂CH₂—. As the alkyl group within the alkylalkylene group, alinear alkyl group of 1 to 5 carbon atoms is preferable.

The linear or branched aliphatic hydrocarbon group may or may not have asubstituent. Examples of the substituent include a fluorine atom, and afluorinated alkyl group of 1 to 5 carbon atoms.

—Aliphatic Hydrocarbon Group Containing a Ring in the Structure Thereof

As examples of the hydrocarbon group containing a ring in the structurethereof, an alicyclic hydrocarbon group (a group in which two hydrogenatoms have been removed from an aliphatic hydrocarbon ring) which maycontain a hetero atom in the ring structure, a group in which thealicyclic hydrocarbon group is bonded to the terminal of theaforementioned chain-like aliphatic hydrocarbon group, and a group inwhich the alicyclic group is interposed within the aforementioned linearor branched aliphatic hydrocarbon group, may be given. As the linear orbranched aliphatic hydrocarbon group, the same groups as those describedabove can be used.

The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms, andmore preferably 3 to 12 carbon atoms.

The alicyclic hydrocarbon group may be either a polycyclic group or amonocyclic group. As the monocyclic aliphatic hydrocarbon group, a groupin which 2 hydrogen atoms have been removed from a monocycloalkane ispreferable. The monocycloalkane preferably has 3 to 6 carbon atoms, andspecific examples thereof include cyclopentane and cyclohexane. As thepolycyclic group, a group in which 2 hydrogen atoms have been removedfrom a polycycloalkane is preferable, and the polycyclic grouppreferably has 7 to 12 carbon atoms. Examples of the polycycloalkaneinclude adamantane, norbornane, isobornane, tricyclodecane andtetracyclododecane.

The alicyclic hydrocarbon group may or may not have a substituent.Examples of the substituent include an alkyl group, a halogen atom and ahalogenated alkyl group.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is particularly desirable.

The halogen atom as the substituent is preferably a fluorine atom.

Examples of the halogenated alkyl group for the substituent includegroups in which part or all of the hydrogen atoms within theaforementioned alkyl groups has been substituted with the aforementionedhalogen atoms.

The alicyclic hydrocarbon group may have part of the carbon atomsconstituting the ring structure thereof substituted with a substituentcontaining a hetero atom (excluding oxygen). Examples of the substituentcontaining a hetero atom include —S—.

—Aromatic Hydrocarbon Group for Ya^(x0)

The aromatic hydrocarbon group is a hydrocarbon group having at leastone aromatic ring.

The aromatic ring is not particularly limited, as long as it is a cyclicconjugated compound having (4n+2)π electrons, and may be eithermonocyclic or polycyclic. The aromatic ring preferably has 5 to 30carbon atoms, more preferably 5 to 20 carbon atoms, and still morepreferably 6 to 15 carbon atoms, and most preferably 6 to 12 carbonatoms. Here, the number of carbon atoms within a substituent(s) is notincluded in the number of carbon atoms of the aromatic hydrocarbongroup. Specific examples of the aromatic ring include an aromatichydrocarbon ring, such as benzene, naphthalene, anthracene orphenanthrene; and an aromatic hetero ring in which part of the carbonatoms constituting the above aromatic hydrocarbon ring has beensubstituted with a hetero atom (excluding oxygen). Examples of thehetero atom within the aromatic hetero rings include a sulfur atom and anitrogen atom. Specific examples of the aromatic hetero ring include apyridine ring and a thiophene ring.

Specific examples of the aromatic hydrocarbon group include a group inwhich two hydrogen atoms have been removed from the aforementionedaromatic hydrocarbon ring or aromatic hetero ring (arylene group orheteroarylene group); a group in which two hydrogen atoms have beenremoved from an aromatic compound having two or more aromatic rings(biphenyl, fluorene or the like); and a group in which one hydrogen atomof the aforementioned aromatic hydrocarbon ring or aromatic hetero ringhas been substituted with an alkylene group (a group in which onehydrogen atom has been removed from the aryl group within theaforementioned arylalkyl group such as a benzyl group, a phenethylgroup, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a1-naphthylethyl group, or a 2-naphthylethyl group, or a heteroarylalkylgroup). The alkylene group which is bonded to the aforementioned arylgroup or heteroaryl group preferably has 1 to 4 carbon atoms, morepreferably 1 or 2 carbon atoms, and most preferably 1 carbon atom.

With respect to the aromatic hydrocarbon group, the hydrogen atom withinthe aromatic hydrocarbon group may be substituted with a substituent.For example, the hydrogen atom bonded to the aromatic ring within thearomatic hydrocarbon group may be substituted with a substituent.Examples of the substituent include an alkyl group, a halogen atom and ahalogenated alkyl group.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is particularly desirable.

As the halogen atom and the halogenated alkyl group for the substituent,the same groups as the aforementioned substituent groups forsubstituting a hydrogen atom within the alicyclic hydrocarbon group maybe used.

—Divalent Linking Group Containing a Hetero Atom

In the case where Ya^(x0) is a divalent linking group containing ahetero atom (excluding oxygen), preferable examples of the linking groupinclude —NH—, —NH—C(═NH)— (H may be substituted with a substituent suchas an alkyl group or an acyl group, and —S—.

Among the above examples, as Ya^(x0), a single bond or a linear orbranched alkylene group is preferable, and a single bond is morepreferable.

In formula (a01-1), Wa⁰¹ represents an aromatic hydrocarbon group.

Examples of the aromatic hydrocarbon group for Wa⁰¹ include a group inwhich (n01+1) hydrogen atom(s) have been removed from an aromatic ring.The aromatic ring is not particularly limited, as long as it is a cyclicconjugated compound having (4n+2)π electrons, and may be eithermonocyclic or polycyclic. The aromatic ring preferably has 5 to 30carbon atoms, more preferably 5 to 20 carbon atoms, and still morepreferably 6 to 15 carbon atoms, and most preferably 6 to 12 carbonatoms. Specific examples of the aromatic ring include an aromatichydrocarbon ring, such as benzene, naphthalene, anthracene orphenanthrene; and an aromatic heterocyclic ring in which part of thecarbon atoms constituting the aromatic hydrocarbon ring has beensubstituted with a heteroatom. Examples of the hetero atom within thearomatic hetero rings include an oxygen atom, a sulfur atom and anitrogen atom. Specific examples of the aromatic hetero ring include apyridine ring and a thiophene ring.

Another example of the aromatic hydrocarbon group for Wa⁰¹ include agroup obtained by removing (n01+1) hydrogen atom(s) from an aromaticcompound having two or more aromatic rings which may have a substituent(e.g., biphenyl or fluorene).

Among the above examples, as Wa⁰¹, a group in which (n01+1) hydrogenatom(s) has been removed from benzene, naphthalene, anthracene orbiphenyl is preferable, a group in which (n01+1) hydrogen atom(s) hasbeen removed from benzene or naphthalene is more preferable, and a groupin which (n01+1) hydrogen atom(s) has been removed from benzene is stillmore preferable.

Part or all of the hydrogen atoms of the aromatic hydrocarbon group (inparticular, a group in which (n01+1) hydrogen atom(s) has been removedfrom benzene) may be substituted with a substituent other that a hydroxygroup. Examples of the substituent include a carboxy group, a halogenatom, an alkoxy group (such as a methoxy group, an ethoxy group, apropoxy group or a butoxy group), and an alkyloxycarbonyl group.

In formula (a01-1), Wa⁰¹ may form a condensed ring together with W⁰¹.

In the case where Wa⁰¹ forms a condensed ring together with W⁰¹,examples of the ring structure include a condensed ring of an alicyclicgroup and an aromatic hydrocarbon group. The condensed ring formed byWa⁰¹ and W⁰¹ may contain a hetero atom.

In the condensed ring formed by Wa⁰¹ and W⁰¹, the alicyclic hydrocarbonportion may be monocyclic or polycyclic.

Examples of the condensed ring formed by Wa⁰¹ and W⁰¹ include acondensed ring formed by the polymerizable group of W⁰¹ and Wa⁰¹, and acondensed ring formed by the group other than the polymerizable groupwithin W⁰¹ and Wa⁰¹.

The condensed ring formed by Wa⁰¹ and W⁰¹ may have a substituent.Examples of the substituent include a methyl group, an ethyl group, apropyl group, a hydroxy group, a hydroxyalkyl group, a carboxy group, ahalogen atom, an alkoxy group (such as a methoxy group, an ethoxy group,a propoxy group or a butoxy group), an acyl group, an alkyloxycarbonylgroup, and an alkylcarbonyloxy group.

Specific examples of the condensed ring formed by Wa⁰¹ and W⁰¹ are shownbelow. W^(α1) represents a polymerizable group. ** represents a bondingsite where the hydroxy group (—(OH)_(n01)) is bonded.

In formula (a01-1), n01 is 1 or 2, preferably 1.

Preferable examples of the structural unit (a01) include a structuralunit represented by general formula (a01-11) shown below.

In formula (a01-11), R⁰¹ represents a hydrogen atom, an alkyl group of 1to 5 carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms;Wa⁰¹ represents an aromatic hydrocarbon group; part or all of thehydrogen atoms of the aromatic hydrocarbon group may be substituted witha substituent other that a hydroxy group; and n01 represents 1 or 2.

In formula (a01-11), as the alkyl group of 1 to 5 carbon atoms for R⁰¹,a linear or branched alkyl group of 1 to 5 carbon atoms is preferable,and specific examples thereof include a methyl group, an ethyl group, apropyl group, an isopropyl group, an n-butyl group, an isobutyl group, atert-butyl group, a pentyl group, an isopentyl group and a neopentylgroup. The halogenated alkyl group of 1 to 5 carbon atoms represented byR is a group in which part or all of the hydrogen atoms of theaforementioned alkyl group of 1 to 5 carbon atoms have been substitutedwith halogen atoms. As the halogen atom, a fluorine atom is mostpreferable.

As R⁰¹, a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or afluorinated alkyl group of 1 to 5 carbon atoms is preferable, and ahydrogen atom or a methyl group is particularly desirable in terms ofindustrial availability.

In formula (a01-11), Wa⁰¹ and n01 are the same as defined above forformula (a01-1).

Specific examples of the structural unit (a01) represented by formula(a01-1) are shown below.

In the formulae shown below, R^(α) represents a hydrogen atom, a methylgroup or a trifluoromethyl group.

Among these examples, as the structural unit (a01), at least one memberselected from the group consisting of structural units represented byany of chemical formulae (a01-1-01) to (a01-1-08) is preferable, and astructural unit represented by chemical formula (a01-1-01) is morepreferable.

As the structural unit (a01) contained in the component (A1), 1 kind ofstructural unit may be used, or 2 or more kinds of structural units maybe used.

In the component (A1), the amount of the structural unit (a01) based onthe combined total (100 mol %) of all structural units constituting thecomponent (A1) is preferably 5 to 70 mol %, more preferably 10 to 60 mol%, still more preferably 15 to 50 mol %, and most preferably 20 to 40mol %.

When the amount of the structural unit (a01) is within theabove-mentioned preferable range, proton source ability and solubilityin a developing solution may be reliably assured, and the effects of thepresent invention may be more reliably achieved.

<<Structural Unit (a02)>>

The structural unit (a02) is a structural unit derived from a compoundrepresented by general formula (a02-1) shown below.

In formula (a02-1), W⁰² represents a polymerizable group-containinggroup; provided that the polymerizable group-containing group for W⁰²contains an oxygen atom; Wa⁰² represents an aromatic hydrocarbon group;part or all of the hydrogen atoms of the aromatic hydrocarbon group maybe substituted with a substituent other that a hydroxy group; Wa⁰² andW⁰² may form a condensed ring; and n02 represents 1 or 2.

In formula (a02-1), the “polymerizable group” for W⁰² is a group whichcan cause a compound having the polymerizable group to be polymerized byradical polymerization or the like. Examples of the polymerizable groupinclude a multiple bond between carbon atoms, such as an ethylenicdouble bond.

In the structural unit (a02), the multiple bond in the polymerizablegroup of the compound represented by the aforementioned general formula(a02-1) is cleaved to form a main chain.

Examples of the polymerizable group include a vinyl group, an allylgroup, an acryloyl group, a methacryloyl group, a fluorovinyl group, adifluorovinyl group, a trifluorovinyl group, adifluorotrifluoromethylvinyl group, a trifluoroallyl group, aperfluoroallyl group, a trifluoromethylacryloyl group, anonylfluorobutylacryloyl group, a vinyl ether group, afluorine-containing vinyl ether group, an allyl ether group, anfluorine-containing allyl ether group, a styryl group, a vinylnaphthylgroup, a fluorine-containing styryl group, a fluorine-containingvinylnaphthyl group, a norbornyl group, a fluorine-containing norbornylgroup, and a silyl group.

The polymerizable group-containing group may be a group constituted ofonly a polymerizable group, or a group constituted of a polymerizablegroup and a group other than a polymerizable group. Examples of thegroup other than a polymerizable group include a divalent hydrocarbongroup which may have a substituent, and a divalent linking groupcontaining a hetero atom. The polymerizable group-containing group forW⁰² contains an oxygen atom.

Preferable examples of W⁰² include a group represented by chemicalformula: C(R^(X13))(R^(X14))═C(R^(X15))—Ya^(x00)—. R^(X13), R^(X14) andR^(X15) each independently represents a hydrogen atom, an alkyl group of1 to 5 carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms,and Ya^(x00) represents a divalent linking group containing an oxygenatom. Preferable examples of the linking group include —O—, —C(═O)—O—,—C(═O)—, —O—C(═O)—O—, —C(═O)—NH—, —S(═O)₂—, —S(═O)₂—O—, and a grouprepresented by general formula —Y²¹—O—Y²²—, —Y²¹—, —Y²¹—C(═O)—O—,—C(═O)—O—Y²¹—[Y²¹—C(═O)—O]_(m″)—Y²²—, —Y²¹—O—C(═O)—Y²²— or—Y²¹—S(═O)₂—O—Y²²— (in the formulae, Y²¹ and Y²² each independentlyrepresents a divalent hydrocarbon group which may have a substituent, 0represents an oxygen atom, and m″ represents an integer of 0 to 3).Among these examples, Ya^(x00) is preferably —C(═O)—O—.

In formula (a02-1), Wa⁰² is the same as defined for Wa⁰¹ in theaforementioned formula (a01-1).

In formula (a02-1), Wa⁰² may form a condensed ring together with W⁰².

In the case where Wa⁰² and W⁰² form a condensed ring, examples of thering structure include a condensed ring of an alicyclic group and anaromatic hydrocarbon group.

In the condensed ring formed by Wa⁰² and W⁰², the alicyclic hydrocarbonportion may be monocyclic or polycyclic.

Examples of the condensed ring formed by Wa⁰² and W⁰² include acondensed ring formed by the polymerizable group of W⁰² and Wa⁰², and acondensed ring formed by the group other than the polymerizable groupwithin W⁰² and Wa⁰².

The condensed ring formed by Wa⁰² and W⁰² may have a substituent.Examples of the substituent include a methyl group, an ethyl group, apropyl group, a hydroxy group, a hydroxyalkyl group, a carboxy group, ahalogen atom, an alkoxy group (such as a methoxy group, an ethoxy group,a propoxy group or a butoxy group), an acyl group, an alkyloxycarbonylgroup, and an alkylcarbonyloxy group.

Specific examples of the condensed ring formed by Wa⁰² and W⁰² are shownbelow. W^(α2) represents a polymerizable group. ** represents a bondingsite where the hydroxy group (—(OH)_(n02)) is bonded.

In formula (a02-1), n02 is 1 or 2, preferably 1.

Preferable examples of the structural unit (a02) include a structuralunit represented by general formula (a02-11) shown below.

In formula (a02-11), R⁰² represents a hydrogen atom, an alkyl group of 1to 5 carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms;Wa⁰² represents an aromatic hydrocarbon group; part or all of thehydrogen atoms of the aromatic hydrocarbon group may be substituted witha substituent other that a hydroxy group; and n02 represents 1 or 2.

In formula (a02-11), as the alkyl group of 1 to 5 carbon atoms for R⁰²,a linear or branched alkyl group of 1 to 5 carbon atoms is preferable,and specific examples thereof include a methyl group, an ethyl group, apropyl group, an isopropyl group, an n-butyl group, an isobutyl group, atert-butyl group, a pentyl group, an isopentyl group and a neopentylgroup. The halogenated alkyl group of 1 to 5 carbon atoms represented byR is a group in which part or all of the hydrogen atoms of theaforementioned alkyl group of 1 to 5 carbon atoms have been substitutedwith halogen atoms. As the halogen atom, a fluorine atom is mostpreferable.

As R⁰², a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or afluorinated alkyl group of 1 to 5 carbon atoms is preferable, and ahydrogen atom or a methyl group is particularly desirable in terms ofindustrial availability.

In formula (a02-11), Wa⁰² and n02 are the same as defined above forformula (a02-1).

Specific examples of the structural unit (a02) represented by formula(a02-1) are shown below.

In the formulae shown below, R^(α) represents a hydrogen atom, a methylgroup or a trifluoromethyl group.

Among these examples, as the structural unit (a02), at least one memberselected from the group consisting of structural units represented byany of chemical formulae (a02-1-01) to (a02-1-03) is preferable, and astructural unit represented by chemical formula (a02-1-01) is morepreferable.

As the structural unit (a02) contained in the component (A1), 1 kind ofstructural unit may be used, or 2 or more kinds of structural units maybe used.

In the component (A), the amount of the structural unit (a02) based onthe combined total (100 mol %) of all structural units constituting thecomponent (A1) is preferably 5 to 70 mol %, more preferably 10 to 60 mol%, still more preferably 15 to 50 mol %, and most preferably 20 to 40mol %.

When the amount of the structural unit (a02) is within theabove-mentioned preferable range, proton source ability and solubilityin a developing solution may be reliably assured, and the effects of thepresent invention may be more reliably achieved.

<<Structural Unit (a03)>>

The structural unit (a03) is a structural unit derived from a compoundrepresented by general formula (a03-1) shown below.

In formula (a03-1), W⁰³ represents a polymerizable group-containinggroup; provided that the polymerizable group-containing grouprepresented by W⁰³ may contain an oxygen atom; Ya⁰³ represents a carbonatom; Xa⁰³ represents a group which forms an alicyclic hydrocarbon grouptogether with Ya⁰³; Ra⁰⁰ represents a hydrocarbon group which may have asubstituent.

In formula (a03-1), the “polymerizable group” for W⁰³ is a group whichcan cause a compound having the polymerizable group to be polymerized byradical polymerization or the like. Examples of the polymerizable groupinclude a multiple bond between carbon atoms, such as an ethylenicdouble bond.

In the structural unit (a03), the multiple bond in the polymerizablegroup of the compound represented by the aforementioned general formula(a03-1) is cleaved to form a main chain.

The polymerizable group-containing group may be a group constituted ofonly a polymerizable group, or a group constituted of a polymerizablegroup and a group other than a polymerizable group. Examples of thegroup other than a polymerizable group include a divalent hydrocarbongroup which may have a substituent, and a divalent linking groupcontaining a hetero atom.

In formula (a03-1), W⁰³ may be a polymerizable group-containing groupcontaining no oxygen as for W⁰¹ in the aforementioned formula (a01-1),or a polymerizable group-containing group containing an oxygen as forW⁰² in the aforementioned formula (a02-1).

The alicyclic hydrocarbon group formed by Xa⁰³ together with Ya⁰³ may bea polycyclic group or a monocyclic group. As the monocyclic aliphatichydrocarbon group, a group in which 2 hydrogen atoms have been removedfrom a monocycloalkane is preferable. The monocycloalkane preferably has3 to 6 carbon atoms, and specific examples thereof include cyclopentaneand cyclohexane. As the polycyclic group, a group in which 2 hydrogenatoms have been removed from a polycycloalkane is preferable, and thepolycyclic group preferably has 7 to 12 carbon atoms. Examples of thepolycycloalkane include adamantane, norbornane, isobornane,tricyclodecane and tetracyclododecane.

Among these examples, as the alicyclic hydrocarbon group formed by Xa⁰³together with Ya⁰³ a monocyclic alicyclic hydrocarbon group ispreferable, cyclopentane or cyclohexane is more preferable, andcyclopentane is still more preferable.

Ra⁰⁰ represents a hydrocarbon group which may have a substituent.Examples of the hydrocarbon group include a linear or branched alkylgroup, a chain or cyclic alkenyl group, and a cyclic group (a monocyclicalicyclic hydrocarbon group, a polycyclic alicyclic hydrocarbon group oran aromatic hydrocarbon group). Examples of substituents include ahydroxy group, a carboxy group, a halogen atom, an alkoxy group, and analkyloxycarbonyl group.

The linear alkyl group preferably has 1 to 5 carbon atoms, morepreferably 1 to 4 carbon atoms, and still more preferably 1 or 2 carbonatoms. Specific examples include a methyl group, an ethyl group, ann-propyl group, an n-butyl group and an n-pentyl group. Among these, amethyl group, an ethyl group or an n-butyl group is preferable, and amethyl group or an ethyl group is more preferable.

The branched alkyl group preferably has 3 to 10 carbon atoms, and morepreferably 3 to 5 carbon atoms. Specific examples include an isopropylgroup, an isobutyl group, a tert-butyl group, an isopentyl group, aneopentyl group a 1,1-diethylpropyl group and a 2,2-dimethylbutyl group.Among these, an isopropyl group is preferable.

The chain or cyclic alkenyl group is preferably an alkenyl group having2 to 10 carbon atoms.

The cyclic hydrocarbon group may be an aliphatic hydrocarbon group or anaromatic hydrocarbon group, and may be polycyclic or monocyclic.

As the monocyclic alicyclic hydrocarbon group, a group in which 1hydrogen atom has been removed from a monocycloalkane is preferable. Themonocycloalkane preferably has 3 to 6 carbon atoms, and specificexamples thereof include cyclopentane and cyclohexane.

As the polycyclic alicyclic hydrocarbon group, a group in which 1hydrogen atom has been removed from a polycycloalkane is preferable. Thepolycycloalkane preferably has 7 to 12 carbon atoms, and specificexamples thereof include adamantane, norbornane, isobornane,tricyclodecane and tetracyclododecane.

In the case where the cyclic hydrocarbon group for Ra⁰⁰ is an aromatichydrocarbon group, the aromatic hydrocarbon group is a hydrocarbon grouphaving at least one aromatic ring.

The aromatic ring is not particularly limited, as long as it is a cyclicconjugated compound having (4n+2)π electrons, and may be eithermonocyclic or polycyclic. The aromatic ring preferably has 5 to 30carbon atoms, more preferably 5 to 20 carbon atoms, and still morepreferably 6 to 15 carbon atoms, and most preferably 6 to 12 carbonatoms. Examples of the aromatic ring include aromatic hydrocarbon rings,such as benzene, naphthalene, anthracene and phenanthrene; and aromatichetero rings in which part of the carbon atoms constituting theaforementioned aromatic hydrocarbon rings has been substituted with ahetero atom. Examples of the hetero atom within the aromatic heterorings include an oxygen atom, a sulfur atom and a nitrogen atom.Specific examples of the aromatic hetero ring include a pyridine ringand a thiophene ring.

Specific examples of the aromatic hydrocarbon group for Ra⁰⁰ include agroup in which one hydrogen atom has been removed from theaforementioned aromatic hydrocarbon ring or aromatic hetero ring (anaryl group or heteroaryl group); a group in which one hydrogen atom hasbeen removed from an aromatic compound having two or more aromatic rings(biphenyl, fluorene or the like); and a group in which one hydrogen atomof the aforementioned aromatic hydrocarbon ring or aromatic hetero ringhas been substituted with an alkylene group (an arylalkyl group such asa benzyl group, a phenethyl group, a 1-naphthylmethyl group, a2-naphthylmethyl group, a 1-naphthylethyl group, or a 2-naphthylethylgroup). The alkylene group bonded to the aforementioned aromatichydrocarbon ring or the aromatic hetero ring preferably has 1 to 4carbon atoms, more preferably 1 or 2 carbon atoms, and most preferably 1carbon atom.

The cyclic hydrocarbon group for Ra⁰⁰ may have a substituent. Examplesof the substituent include —R^(P1), —R^(P2)—O—R^(P1), —R^(P2)—CO—R^(P1),—R^(P2)—CO—OR^(P1), —R^(P2)—O—CO—R^(P1), —R²—OH, —R^(P2)—CN and—R^(P2)—COOH (hereafter, these substituents are sometimes collectivelyreferred to as “Ra^(x5)”). R represents a monovalent saturated chainhydrocarbon group of 1 to 10 carbon atoms, a monovalent saturated cyclicaliphatic hydrocarbon group of 3 to 20 carbon atoms or a monovalentaromatic hydrocarbon group of 6 to 30 carbon atoms. R^(P2) represents asingle bond, monovalent saturated chain hydrocarbon group of 1 to 10carbon atoms, a monovalent saturated aliphatic cyclic hydrocarbon groupof 3 to 20 carbon atoms or a monovalent aromatic hydrocarbon group of 6to 30 carbon atoms. The saturated chain hydrocarbon group, the saturatedcyclic aliphatic hydrocarbon group and the aromatic hydrocarbon groupfor R^(P1) and R^(P2) may have part or all of the hydrogen atomssubstituted with fluorine. The aliphatic cyclic hydrocarbon group mayhave 1 or more substituents of 1 kind, or 1 or more substituents of aplurality of kinds.

Examples of the monovalent chain saturated hydrocarbon group having 1 to10 carbon atoms include a methyl group, an ethyl group, a propyl group,a butyl group, a pentyl group, a hexyl group, a heptyl group, an octylgroup, and a decyl group.

Examples of the monovalent aliphatic cyclic saturated hydrocarbon grouphaving 3 to 20 carbon atoms include a monocyclic aliphatic saturatedhydrocarbon group such as a cyclopropyl group, a cyclobutyl group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctylgroup, a cyclodecyl group, and a cyclododecyl group; and a polycyclicaliphatic saturated hydrocarbon group such as a bicyclo[2.2.2]octanylgroup, a tricyclo[5.2.1.02,6]decanyl group, atricyclo[3.3.1.13,7]decanyl group, atetracyclo[6.2.1.13,6.02,7]dodecanyl group, and an adamantyl group.

Examples of the monovalent aromatic hydrocarbon group having 6 to 30carbon atoms include a group obtained by removing one hydrogen atom fromthe aromatic hydrocarbon ring such as benzene, biphenyl, fluorene,naphthalene, anthracene, and phenanthrene.

Among the above examples, in formula (a03-1), Ra⁰⁰ is preferably a chainalkenyl group or an aromatic hydrocarbon group.

Preferable examples of the structural unit (a03) include a structuralunit represented by general formula (a03-11) or (a03-12) shown below.

In formula (a03-11), R⁰³ represents a hydrogen atom, an alkyl group of 1to 5 carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms;Ya⁰³ represents a carbon atom; Xa⁰³ represents a group which forms analicyclic hydrocarbon group together with Ya⁰³; Ra⁰⁰¹ to Ra⁰⁰³ eachindependently represents a hydrogen atom, a monovalent saturated chainhydrocarbon group of 1 to 10 carbon atoms or a monovalent saturatedaliphatic cyclic hydrocarbon group of 3 to 20 carbon atoms, providedthat part or all of the hydrogen atoms of the saturated chainhydrocarbon or the saturated aliphatic cyclic hydrocarbon may besubstituted; two or more of Ra⁰⁰¹ to Ra⁰⁰³ may be mutually bonded toform a ring structure.

In formula (a03-12), R⁰³ represents a hydrogen atom, an alkyl group of 1to 5 carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms;Ya⁰³ represents a carbon atom; Xa⁰³ represents a group which forms analicyclic hydrocarbon group together with Ya⁰³; and Ra⁰⁰⁴ represents anaromatic hydrocarbon group which may have a substituent.

In general formulae (a03-11) and (a03-12), R⁰³, Ya⁰³ and Xa⁰³ are thesame as defined for R⁰³, Ya⁰³ and Xa⁰³ in the aforementioned generalformula (a03-1), respectively.

In general formula (a03-11), Ra⁰⁰¹ to Ra⁰²⁰³ each independentlyrepresents a hydrogen atom, a monovalent saturated chain hydrocarbongroup of 1 to 10 carbon atoms or a monovalent saturated aliphatic cyclichydrocarbon group of 3 to 20 carbon atoms,

Examples of the monovalent chain saturated hydrocarbon group having 1 to10 carbon atoms include a methyl group, an ethyl group, a propyl group,a butyl group, a pentyl group, a hexyl group, a heptyl group, an octylgroup, and a decyl group.

Examples of the monovalent aliphatic cyclic saturated hydrocarbon grouphaving 3 to 20 carbon atoms include a monocyclic aliphatic saturatedhydrocarbon group such as a cyclopropyl group, a cyclobutyl group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctylgroup, a cyclodecyl group, and a cyclododecyl group; and a polycyclicaliphatic saturated hydrocarbon group such as a bicyclo[2.2.2]octanylgroup, a tricyclo[5.2.1.02,6]decanyl group, atricyclo[3.3.1.13,7]decanyl group, atetracyclo[6.2.1.13,6.02,7]dodecanyl group, and an adamantyl group.

In general formula (a03-11), in terms of ease in synthesis, Ra⁰⁰¹ toRa⁰⁰³ is preferably a hydrogen atom or a monovalent saturatedhydrocarbon group having 1 to 10 carbon atoms, more preferably ahydrogen atom, a methyl group or an ethyl group, and most preferably ahydrogen atom.

As the substituent for the saturated chain hydrocarbon group orsaturated cyclic aliphatic hydrocarbon group represented by Ra⁰⁰¹ toRa⁰⁰³, for example, the same substituents as those described above forRa^(x5) may be mentioned.

Examples of the group containing a carbon-carbon double bond which isgenerated by forming a cyclic structure in which two or more of Ra⁰⁰¹ toRa⁰⁰³ are bonded to each other include a cyclopentenyl group, acyclohexenyl group, a methyl cyclopentenyl group, a methyl cyclohexenylgroup, a cyclopentylideneethenyl group, and a cyclohexylidenethenylgroup. Among these examples, in terms of ease in synthesis of themonomeric compound, a cyclopentenyl group, a cyclohexenyl group or acyclopentylidenyl group is preferable.

In general formula (a03-12), Ra⁰⁰⁴ represents an aromatic hydrocarbongroup, and is the same as defined for Ra⁰⁰.

Specific examples of the structural unit (a03) are shown below. In theformulae shown below, R^(α) represents a hydrogen atom, a methyl groupor a trifluoromethyl group.

As the structural unit (a03) contained in the component (A1), 1 kind ofstructural unit may be used, or 2 or more kinds of structural units maybe used.

In the component (A1), the amount of the structural unit (a03) based onthe combined total (100 mol %) of all structural units constituting thecomponent (A1) is preferably 5 to 80 mol %, more preferably 10 to 70 mol%, and still more preferably 30 to 60 mol %.

When the amount of the structural unit (a03) is within theabove-mentioned preferable range, efficiency of the deprotectionreaction and solubility in a developing solution may be reliablyassured, and the effects of the present invention may be more reliablyachieved.

<<Other Structural Units>>

The component (A1) may further include a structural unit other than thestructural units (a01), (a02) and (a03).

Examples of other structural units include a structural unit (a1) otherthan the structural unit (a03) which contains an acid decomposablegroup; a structural unit (a2) containing a lactone-containing cyclicgroup, an —SO₂— containing cyclic group or a carbonate-containing cyclicgroup; a structural unit (a3) containing a polar group-containingaliphatic hydrocarbon group; a structural unit (a4) containing an acidnon-dissociable aliphatic cyclic group; and a structural unit (st)derived from styrene or a derivative thereof.

Structural Unit (a1):

The structural unit (a1) is a structural unit other than the structuralunit (a03), and contains an acid decomposable group. Examples of theacid dissociable group which constitutes the acid decomposable groupinclude groups which have been proposed as acid dissociable groups forthe base resin of a conventional chemically amplified resistcomposition.

Specific examples of acid dissociable groups for the base resin of aconventional chemically amplified resist composition include“acetal-type acid dissociable group”, “tertiary alkyl ester-type aciddissociable group” and “tertiary alkyloxycarbonyl acid dissociablegroup” described below.

—Acetal-Type Acid Dissociable Group

Examples of the acid dissociable group for protecting the carboxy groupor hydroxy group as a polar group include the acid dissociable grouprepresented by general formula (a1-r-1) shown below (hereafter, referredto as “acetal-type acid dissociable group”).

In the formula, Ra′¹ and Ra′² each independently represents a hydrogenatom or an alkyl group; Ra′³ represents a hydrocarbon group, providedthat Ra′³ may be bonded to Ra′¹ or Ra′² to form a ring.

In the formula (a1-r-1), it is preferable that at least one of Ra′¹ andRa′² represents a hydrogen atom, and it is more preferable that both ofRa′¹ and Ra′² represent a hydrogen atom.

In the case where Ra′¹ or Ra′² is an alkyl group, as the alkyl group,the same alkyl groups as those described above the for the substituentwhich may be bonded to the carbon atom on the α-position of theaforementioned α-substituted acrylate ester can be mentioned, and analkyl group of 1 to 5 carbon atoms is preferable. Specific examplesinclude linear or branched alkyl groups. Specific examples of the alkylgroup include a methyl group, an ethyl group, a propyl group, anisopropyl group, an n-butyl group, an isobutyl group, a tert-butylgroup, a pentyl group, an isopentyl group and a neopentyl group. Ofthese, a methyl group or an ethyl group is preferable, and a methylgroup is particularly preferable.

In formula (a1-r-1), examples of the hydrocarbon group for Ra′³ includea linear or branched alkyl group and a cyclic hydrocarbon group. Thelinear or branched alkyl group and the cyclic hydrocarbon group are thesame as defined for Ra⁰⁰ in the aforementioned general formula (a03-1).

The cyclic hydrocarbon group for Ra′³ may have a substituent. Examplesof the substituent include the aforementioned Ra^(x5).

In the case where Ra′³ is bonded to Ra′¹ or Ra′² to form a ring, thecyclic group is preferably a 4 to 7-membered ring, and more preferably a4 to 6-membered ring. Specific examples of the cyclic group includetetrahydropyranyl group and tetrahydrofuranyl group.

—Tertiary Alkyl Ester-Type Acid Dissociable Group

Examples of the acid dissociable group for protecting the carboxy groupas a polar group include the acid dissociable group represented bygeneral formula (a1-r-2) shown below.

Among the acid dissociable groups represented by general formula(a1-r-2), for convenience, a group which is constituted of alkyl groupsis referred to as “tertiary ester-type acid dissociable group”.

In the formula, Ra′⁴ to Ra′⁶ each independently represents a hydrocarbongroup.

Examples of the hydrocarbon group for Ra′⁴ include a linear or branchedalkyl group, a chain or cyclic alkenyl group, and a cyclic hydrocarbongroup.

The linear or branched alkyl group and the cyclic hydrocarbon group(monocyclic aliphatic hydrocarbon group, polycyclic aliphatichydrocarbon group or aromatic hydrocarbon group) for Ra′⁴ are the sameas defined for Ra′³.

The chain or cyclic alkenyl group for Ra′⁴ is preferably an alkenylgroup having 2 to 10 carbon atoms.

The hydrocarbon group for Ra′⁵ and Ra′⁶ is the same as defined for Ra′³.

Preferable examples of the tertiary alkyl ester-type acid dissociablegroup include a group represented by general formula (a1-r2-4) shownbelow.

In general formula (a1-r2-4), Ra′¹² and Ra′¹³ each independentlyrepresent a monovalent chain saturated hydrocarbon group having 1 to 10carbon atoms or a hydrogen atom, provided that part or all of thehydrogen atoms of the saturated hydrocarbon group may be substituted;Ra′¹⁴ represents a hydrocarbon group which may have a substituent; and *represents a valence bond.

In general formula (a1-r2-4), Ra′¹² and Ra′¹³ each independentlyrepresent a monovalent chain saturated hydrocarbon group having 1 to 10carbon atoms or a hydrogen atom, provided that part or all of thehydrogen atoms of the saturated hydrocarbon group may be substituted.

Among these examples, as Ra′¹² and Ra′¹³, a hydrogen atom and an alkylgroup having 1 to 5 carbon atoms are preferable, an alkyl group having 1to 5 carbon atoms is further preferable, a methyl group and an ethylgroup are still further preferable, and a methyl group is particularlypreferable.

In the case where the chain saturated hydrocarbon group represented byRa′¹² and Ra′¹³ is substituted, examples of the substituent include thesame group as that of Ra^(x5).

In general formula (a1-r2-4), Ra′¹⁴ is a hydrocarbon group which mayhave a substituent. Examples of the hydrocarbon group for Ra′¹⁴ includea linear or branched alkyl group and a cyclic hydrocarbon group.

The linear alkyl group for Ra′¹⁴ preferably has 1 to 5 carbon atoms,more preferably 1 to 4 carbon atoms, and still more preferably 1 or 2carbon atoms. Specific examples include a methyl group, an ethyl group,an n-propyl group, an n-butyl group and an n-pentyl group. Among these,a methyl group, an ethyl group or an n-butyl group is preferable, and amethyl group or an ethyl group is more preferable.

The branched alkyl group for Ra′¹⁴ preferably has 3 to 10 carbon atoms,and more preferably 3 to 5 carbon atoms. Specific examples include anisopropyl group, an isobutyl group, a tert-butyl group, an isopentylgroup, a neopentyl group a 1,1-diethylpropyl group and a2,2-dimethylbutyl group. Among these, an isopropyl group is preferable.

In the case where Ra′¹⁴ represents a cyclic hydrocarbon group, thecyclic hydrocarbon group may be an aliphatic hydrocarbon group or anaromatic hydrocarbon group, and may be polycyclic or monocyclic.

As the monocyclic aliphatic hydrocarbon group, a group in which 1hydrogen atom has been removed from a monocycloalkane is preferable. Themonocycloalkane preferably has 3 to 6 carbon atoms, and specificexamples thereof include cyclopentane and cyclohexane.

As the polycyclic aliphatic hydrocarbon group, a group in which 1hydrogen atom has been removed from a polycycloalkane is preferable, andthe polycyclic group preferably has 7 to 12 carbon atoms. Examples ofthe polycycloalkane include adamantane, norbornane, isobornane,tricyclodecane and tetracyclododecane.

The aromatic hydrocarbon group for Ra′¹⁴, is preferably a group obtainedby removing one or more hydrogen atoms from an aromatic hydrocarbon ringhaving 6 to 15 carbon atoms, a group obtained by removing one or morehydrogen atoms from benzene, naphthalene, anthracene, or phenanthrene isfurther preferable, a group obtained by removing one or more hydrogenatoms from benzene, naphthalene, or anthracene is still furtherpreferable, a group obtained by removing one or more hydrogen atoms fromnaphthalene or anthracene is particularly preferable, and a groupobtained by removing one or more hydrogen atoms from naphthalene is mostpreferable.

In the case where Ra′¹⁴ in general formula (a1-r2-4) is a naphthylgroup, a position which is bonded to a tertiary carbon atom in generalformula (a1-r2-4) may be 1-position and 2-position of the naphthylgroup.

In the case where Ra′¹⁴ in general formula (a1-r2-4) is an anthrylgroup, a position which is bonded to a tertiary carbon atom in generalformula (a1-r2-4) may be any one of 1-position, 2-position, and9-position of the anthryl group.

Specific examples of the group represented by the aforementioned formula(a1-r2-4) are shown below.

—Tertiary Alkyloxycarbonyl Acid Dissociable Group

Examples of the acid dissociable group for protecting a hydroxy group asa polar group include the acid dissociable group represented by generalformula (a1-r-3) shown below (hereafter, for convenience, referred to as“tertiary alkyloxycarbonyl-type acid dissociable group”).

In the formula, Ra′⁷ to Ra′⁹ each independently represents an alkylgroup.

In formula (a1-r-3), each of Ra′⁷ to Ra′⁹ is preferably an alkyl grouphaving 1 to 5 carbon atoms, and more preferably an alkyl group having 1to 3 carbon atoms.

Further, the total number of carbon atoms in the alkyl groups ispreferably 3 to 7, more preferably 3 to 5, and still more preferably 3or 4.

Examples of the structural unit (a1) include a structural unit derivedfrom an acrylate ester which may have the hydrogen atom bonded to thecarbon atom on the α-position substituted with a substituent; astructural unit derived from an acrylamide; a structural unit derivedfrom hydroxystyrene or a hydroxystyrene derivative in which at least apart of the hydrogen atom of the hydroxy group is protected with asubstituent containing an acid decomposable group; and a structural unitderived from vinylbenzoic acid or a vinylbenzoic acid derivative inwhich at least a part of the hydrogen atom within —C(═O)—OH is protectedwith a substituent containing an acid decomposable group.

As the structural unit (a1) contained in the component (A1), 1 type ofstructural unit may be used, or 2 or more types may be used.

Structural Unit (a2):

The component (A1) may further include a structural unit (a2) whichcontains a lactone-containing cyclic group, an —SO₂— containing cyclicgroup or a carbonate-containing cyclic group (provided that structuralunits which fall under the definition of the structural unit (a1) areexcluded).

When the component (A1) is used for forming a resist film, thelactone-containing cyclic group, the —SO₂— containing cyclic group orthe carbonate-containing cyclic group within the structural unit (a2) iseffective in improving the adhesion between the resist film and thesubstrate. In addition, by virtue of containing the structural unit(a2), for example, the acid diffusion length is appropriately adjusted,the adhesion of the resist film to the substrate is enhanced, or thesolubility during development is appropriately adjusted. As a result,the lithography properties are enhanced.

The term “lactone-containing cyclic group” refers to a cyclic groupincluding a ring containing a —O—C(═O)— structure (lactone ring). Theterm “lactone ring” refers to a single ring containing a —O—C(O)—structure, and this ring is counted as the first ring. Alactone-containing cyclic group in which the only ring structure is thelactone ring is referred to as a monocyclic group, and groups containingother ring structures are described as polycyclic groups regardless ofthe structure of the other rings. The lactone-containing cyclic groupmay be either a monocyclic group or a polycyclic group.

The lactone-containing cyclic group for the structural unit (a2) is notparticularly limited, and an arbitrary structural unit may be used.Specific examples include groups represented by general formulae(a2-r-1) to (a2-r-7) shown below.

In the formulae, each Ra′²¹ independently represents a hydrogen atom, analkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group,a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyanogroup; R″ represents a hydrogen atom, an alkyl group, alactone-containing cyclic group, a carbonate-containing cyclic group oran —SO₂— containing cyclic group; A″ represents an oxygen atom (—O—), asulfur atom (—S—) or an alkylene group of 1 to 5 carbon atoms which maycontain an oxygen atom or a sulfur atom; n′ represents an integer of 0to 2; and m′ represents 0 or 1.

In formulae (a2-r-1) to (a2-r-7), the alkyl group for Ra′²¹ ispreferably an alkyl group of 1 to 6 carbon atoms. Further, the alkylgroup is preferably a linear alkyl group or a branched alkyl group.Specific examples include a methyl group, an ethyl group, a propylgroup, an isopropyl group, an n-butyl group, an isobutyl group, atert-butyl group, a pentyl group, an isopentyl group, a neopentyl groupand a hexyl group. Among these, a methyl group or ethyl group ispreferable, and a methyl group is particularly desirable.

The alkoxy group for Ra′²¹ is preferably an alkoxy group of 1 to 6carbon atoms. Further, the alkoxy group is preferably a linear orbranched alkoxy group. Specific examples of the alkoxy groups includethe aforementioned alkyl groups for Ra′²¹ having an oxygen atom (—O—)bonded thereto.

The halogen atom for Ra′²¹ is preferably a fluorine atom.

Examples of the halogenated alkyl group for Ra′²¹ include groups inwhich part or all of the hydrogen atoms within the aforementioned alkylgroup for Ra′²¹ has been substituted with the aforementioned halogenatoms. As the halogenated alkyl group, a fluorinated alkyl group ispreferable, and a perfluoroalkyl group is particularly desirable.

With respect to —COOR″ and —OC(═O)R″ for Ra′²¹, R″ represents a hydrogenatom, an alkyl group, a lactone-containing cyclic group, acarbonate-containing cyclic group or an —SO₂— containing cyclic group.

The alkyl group for R″ may be linear, branched or cyclic, and preferablyhas 1 to 15 carbon atoms.

When R″ represents a linear or branched alkyl group, it is preferably analkyl group of 1 to 10 carbon atoms, more preferably an alkyl group of 1to 5 carbon atoms, and most preferably a methyl group or an ethyl group.

When R″ is a cyclic alkyl group (cycloalkyl group), it preferably has 3to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and mostpreferably 5 to 10 carbon atoms. Specific examples include groups inwhich one or more hydrogen atoms have been removed from amonocycloalkane or a polycycloalkane such as a bicycloalkane,tricycloalkane or tetracycloalkane which may or may not be substitutedwith a fluorine atom or a fluorinated alkyl group. Specific examplesinclude groups in which one or more hydrogen atoms have been removedfrom a monocycloalkane such as cyclopentane or cyclohexane; and groupsin which one or more hydrogen atoms have been removed from apolycycloalkane such as adamantane, norbornane, isobornane,tricyclodecane or tetracyclododecane.

Examples of the lactone-containing cyclic group for R″ include groupsrepresented by the aforementioned general formulae (a2-r-1) to (a2-r-7).

The carbonate-containing cyclic group for R″ is the same as defined forthe carbonate-containing cyclic group described later. Specific examplesof the carbonate-containing cyclic group include groups represented bygeneral formulae (ax3-r-1) to (ax3-r-3).

The —SO₂— containing cyclic group for R″ is the same as defined for the—SO₂-containing cyclic group described later. Specific examples of the—SO₂— containing cyclic group include groups represented by generalformulae (a5-r-1) to (a5-r-4).

The hydroxyalkyl group for Ra′²¹ preferably has 1 to 6 carbon atoms, andspecific examples thereof include the alkyl groups for Ra′²¹ in which atleast one hydrogen atom has been substituted with a hydroxy group.

In formulae (a2-r-2), (a2-r-3) and (a2-r-5), as the alkylene group of 1to 5 carbon atoms represented by A″, a linear or branched alkylene groupis preferable, and examples thereof include a methylene group, anethylene group, an n-propylene group and an isopropylene group. Examplesof alkylene groups that contain an oxygen atom or a sulfur atom includethe aforementioned alkylene groups in which —O— or —S— is bonded to theterminal of the alkylene group or present between the carbon atoms ofthe alkylene group. Specific examples of such alkylene groups includeO—CH₂—, —CH₂—O—CH₂—, —S—CH₂—, and —CH₂—S—CH₂—. As A″, an alkylene groupof 1 to 5 carbon atoms or —O— is preferable, more preferably an alkylenegroup of 1 to 5 carbon atoms, and most preferably a methylene group.

Specific examples of the groups represented by the aforementionedgeneral formulae (a2-r-1) to (a2-r-7) are shown below.

An “—SO₂— containing cyclic group” refers to a cyclic group having aring containing —SO₂— within the ring structure thereof, i.e., a cyclicgroup in which the sulfur atom (S) within —SO₂— forms part of the ringskeleton of the cyclic group. The ring containing —SO₂— within the ringskeleton thereof is counted as the first ring. A cyclic group in whichthe only ring structure is the ring that contains —SO₂— in the ringskeleton thereof is referred to as a monocyclic group, and a groupcontaining other ring structures is described as a polycyclic groupregardless of the structure of the other rings. The —SO₂-containingcyclic group may be either a monocyclic group or a polycyclic group. Asthe —SO₂— containing cyclic group, a cyclic group containing —O—SO₂—within the ring skeleton thereof, i.e., a cyclic group containing asultone ring in which —O—S— within the —O—SO₂— group forms part of thering skeleton thereof is particularly desirable.

More specific examples of the —SO₂— containing cyclic group includegroups represented by general formulas (a5-r-1) to (a5-r-4) shown below.

In the formulae, each Ra′¹ independently represents a hydrogen atom, analkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group,a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyanogroup; R″ represents a hydrogen atom, an alkyl group, alactone-containing cyclic group, a carbonate-containing cyclic group oran —SO₂— containing cyclic group; A″ represents an oxygen atom, a sulfuratom or an alkylene group of 1 to 5 carbon atoms which may contain anoxygen atom or a sulfur atom; and n′ represents an integer of 0 to 2.

In general formulae (a5-r-1) and (a5-r-2), A″ is the same as defined forA″ in general formulae (a2-r-2), (a2-r-3) and (a2-r-5).

Examples of the alkyl group, alkoxy group, halogen atom, halogenatedalkyl group, —COOR″, —OC(═O)R″ and hydroxyalkyl group for Ra′¹ includethe same groups as those described above in the explanation of Ra′²¹ inthe general formulas (a2-r-1) to (a2-r-7).

Specific examples of the groups represented by the aforementionedgeneral formulae (a5-r-1) to (a5-r-4) are shown below. In the formulaeshown below, “Ac” represents an acetyl group.

The term “carbonate-containing cyclic group” refers to a cyclic groupincluding a ring containing a —O—C(═O)—O— structure (carbonate ring).The term “carbonate ring” refers to a single ring containing a—O—C(═O)—O— structure, and this ring is counted as the first ring. Acarbonate-containing cyclic group in which the only ring structure isthe carbonate ring is referred to as a monocyclic group, and groupscontaining other ring structures are described as polycyclic groupsregardless of the structure of the other rings. The carbonate-containingcyclic group may be either a monocyclic group or a polycyclic group.

The carbonate-containing cyclic group is not particularly limited, andan arbitrary group may be used. Specific examples include groupsrepresented by general formulae (ax3-r-1) to (ax3-r-3) shown below.

In the formulae, each Ra′^(x31) independently represents a hydrogenatom, an alkyl group, an alkoxy group, a halogen atom, a halogenatedalkyl group, a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group ora cyano group; R″ represents a hydrogen atom, an alkyl group, alactone-containing cyclic group, a carbonate-containing cyclic group oran —SO₂— containing cyclic group; A″ represents an oxygen atom, a sulfuratom or an alkylene group of 1 to 5 carbon atoms which may contain anoxygen atom or a sulfur atom; p′ represents an integer of 0 to 3; and q′represents 0 or 1.

In general formulae (ax3-r-2) and (ax3-r-3), A″ is the same as definedfor A″ in general formulae (a2-r-2), (a2-r-3) and (a2-r-5).

Examples of the alkyl group, alkoxy group, halogen atom, halogenatedalkyl group, —COOR″, —OC(═O)R″ and hydroxyalkyl group for Ra′³¹ includethe same groups as those described above in the explanation of Ra′²¹ inthe general formulas (a2-r-1) to (a2-r-7).

Specific examples of the groups represented by the aforementionedgeneral formulae (ax3-r-1) to (ax3-r-3) are shown below.

As the structural unit (a2), a structural unit derived from an acrylateester which may have the hydrogen atom bonded to the carbon atom on theα-position substituted with a substituent is preferable.

The structural unit (a2) is preferably a structural unit represented bygeneral formula (a2-1) shown below.

In the formula, R represents a hydrogen atom, an alkyl group of 1 to 5carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms; Ya²¹represents a single bond or a divalent linking group; La²¹ represents—O—, —COO—, —CON(R′)—, —OCO—, —CONHCO— or —CONHCS—; and R′ represents ahydrogen atom or a methyl group; provided that, when La²¹ represents—O—, Ya²¹ does not represents —CO—; and Ra²¹ represents alactone-containing cyclic group, a carbonate-containing cyclic group oran —SO₂— containing cyclic group.

In the formula (a2-1), R is the same as defined above. As R, a hydrogenatom, an alkyl group of 1 to 5 carbon atoms or a fluorinated alkyl groupof 1 to 5 carbon atoms is preferable, and a hydrogen atom or a methylgroup is particularly desirable in terms of industrial availability.

In the formula (a2-1), the divalent linking group for Ya²¹ is notparticularly limited, and preferable examples thereof include a divalenthydrocarbon group which may have a substituent and a divalent linkinggroup containing a hetero atom.

—Divalent Hydrocarbon Group which May have a Substituent:

In the case where Ya²¹ is a divalent linking group which may have asubstituent, the hydrocarbon group may be either an aliphatichydrocarbon group or an aromatic hydrocarbon group.

—Aliphatic Hydrocarbon Group for Ya²¹

An “aliphatic hydrocarbon group” refers to a hydrocarbon group that hasno aromaticity. The aliphatic hydrocarbon group may be saturated orunsaturated. In general, the aliphatic hydrocarbon group is preferablysaturated. Examples of the aliphatic hydrocarbon group include a linearor branched aliphatic hydrocarbon group, and an aliphatic hydrocarbongroup containing a ring in the structure thereof can be given.

—Linear or Branched Aliphatic Hydrocarbon Group

The linear aliphatic hydrocarbon group preferably has 1 to 10 carbonatoms, more preferably 1 to 6, still more preferably 1 to 4, and mostpreferably 1 to 3.

As the linear aliphatic hydrocarbon group, a linear alkylene group ispreferable. Specific examples thereof include a methylene group [—CH₂—],an ethylene group [—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], atetramethylene group [—(CH₂)₄-] and a pentamethylene group [—(CH₂)₅—].

The branched aliphatic hydrocarbon group preferably has 2 to 10 carbonatoms, more preferably 3 to 6, still more preferably 3 or 4, and mostpreferably 3.

As the branched aliphatic hydrocarbon group, branched alkylene groupsare preferred, and specific examples include various alkylalkylenegroups, including alkylmethylene groups such as —CH(CH₃)—, —CH(CH₂CH₃)—,—C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)—, and —C(CH₂CH₃)₂—;alkylethylene groups such as —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—,—C(CH₃)₂CH₂—, —CH(CH₂CH₃)CH₂—, and —C(CH₂CH₃)₂—CH₂—; alkyltrimethylenegroups such as —CH(CH₃)CH₂CH₂—, and —CH₂CH(CH₃)CH₂—; andalkyltetramethylene groups such as —CH(CH₃)CH₂CH₂CH₂—, and—CH₂CH(CH₃)CH₂CH₂—. As the alkyl group within the alkylalkylene group, alinear alkyl group of 1 to 5 carbon atoms is preferable.

The linear or branched aliphatic hydrocarbon group may or may not have asubstituent. Examples of the substituent include a fluorine atom, afluorinated alkyl group of 1 to 5 carbon atoms, and a carbonyl group.

—Aliphatic Hydrocarbon Group Containing a Ring in the Structure Thereof

As examples of the hydrocarbon group containing a ring in the structurethereof, an alicyclic hydrocarbon group (a group in which two hydrogenatoms have been removed from an aliphatic hydrocarbon ring) which mayhave a substituent containing a hetero atom in the ring structurethereof, a group in which the alicyclic hydrocarbon group is bonded tothe terminal of the aforementioned chain-like aliphatic hydrocarbongroup, and a group in which the alicyclic group is interposed within theaforementioned linear or branched aliphatic hydrocarbon group, may begiven. As the linear or branched aliphatic hydrocarbon group, the samegroups as those described above can be used.

The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms, andmore preferably 3 to 12 carbon atoms.

The alicyclic hydrocarbon group may be either a polycyclic group or amonocyclic group. As the monocyclic aliphatic hydrocarbon group, a groupin which 2 hydrogen atoms have been removed from a monocycloalkane ispreferable. The monocycloalkane preferably has 3 to 6 carbon atoms, andspecific examples thereof include cyclopentane and cyclohexane. As thepolycyclic group, a group in which 2 hydrogen atoms have been removedfrom a polycycloalkane is preferable, and the polycyclic grouppreferably has 7 to 12 carbon atoms. Examples of the polycycloalkaneinclude adamantane, norbornane, isobornane, tricyclodecane andtetracyclododecane.

The alicyclic hydrocarbon group may or may not have a substituent.Examples of the substituent include an alkyl group, an alkoxy group, ahalogen atom, a halogenated alkyl group, a hydroxyl group and a carbonylgroup.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and more preferably a methyl group, an ethyl group, apropyl group, an n-butyl group or a tert-butyl group.

The alkoxy group as the substituent is preferably an alkoxy group having1 to 5 carbon atoms, more preferably a methoxy group, ethoxy group,n-propoxy group, iso-propoxy group, n-butoxy group or tert-butoxy group,and still more preferably a methoxy group or an ethoxy group.

The halogen atom as the substituent is preferably a fluorine atom.

Examples of the halogenated alkyl group for the substituent includegroups in which part or all of the hydrogen atoms within theaforementioned alkyl groups has been substituted with the aforementionedhalogen atoms.

The alicyclic hydrocarbon group may have part of the carbon atomsconstituting the ring structure thereof substituted with a substituentcontaining a hetero atom. As the substituent containing a hetero atom,—O—, —C(═O)—O—, —S—, —S(═O)₂— or —S(═O)₂—O— is preferable.

—Aromatic Hydrocarbon Group for Ya²¹

The aromatic hydrocarbon group is a hydrocarbon group having at leastone aromatic ring.

The aromatic ring is not particularly limited, as long as it is a cyclicconjugated compound having (4n+2)π electrons, and may be eithermonocyclic or polycyclic. The aromatic ring preferably has 5 to 30carbon atoms, more preferably 5 to 20 carbon atoms, and still morepreferably 6 to 15 carbon atoms, and most preferably 6 to 12 carbonatoms. Here, the number of carbon atoms within a substituent(s) is notincluded in the number of carbon atoms of the aromatic hydrocarbongroup.

Examples of the aromatic ring include aromatic hydrocarbon rings, suchas benzene, naphthalene, anthracene and phenanthrene; and aromatichetero rings in which part of the carbon atoms constituting theaforementioned aromatic hydrocarbon rings has been substituted with ahetero atom. Examples of the hetero atom within the aromatic heterorings include an oxygen atom, a sulfur atom and a nitrogen atom.Specific examples of the aromatic hetero ring include a pyridine ringand a thiophene ring.

Specific examples of the aromatic hydrocarbon group include a group inwhich two hydrogen atoms have been removed from the aforementionedaromatic hydrocarbon ring or aromatic hetero ring (arylene group orheteroarylene group); a group in which two hydrogen atoms have beenremoved from an aromatic compound having two or more aromatic rings(biphenyl, fluorene or the like); and a group in which one hydrogen atomof the aforementioned aromatic hydrocarbon ring or aromatic hetero ringhas been substituted with an alkylene group (a group in which onehydrogen atom has been removed from the aryl group within theaforementioned arylalkyl group such as a benzyl group, a phenethylgroup, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a1-naphthylethyl group, or a 2-naphthylethyl group, or a heteroarylalkylgroup). The alkylene group which is bonded to the aforementioned arylgroup or heteroaryl group preferably has 1 to 4 carbon atoms, morepreferably 1 or 2 carbon atoms, and most preferably 1 carbon atom.

With respect to the aromatic hydrocarbon group, the hydrogen atom withinthe aromatic hydrocarbon group may be substituted with a substituent.For example, the hydrogen atom bonded to the aromatic ring within thearomatic hydrocarbon group may be substituted with a substituent.Examples of substituents include an alkyl group, an alkoxy group, ahalogen atom, a halogenated alkyl group, and a hydroxyl group.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and more preferably a methyl group, an ethyl group, apropyl group, an n-butyl group or a tert-butyl group.

As the alkoxy group, the halogen atom and the halogenated alkyl groupfor the substituent, the same groups as the aforementioned substituentgroups for substituting a hydrogen atom within the alicyclic hydrocarbongroup may be used.

—Divalent Linking Group Containing a Hetero Atom

In the case where Ya²¹ is a divalent linking group containing a heteroatom, examples of the linking group include —O—, —C(═O)—O—, —O—C(═O)—,—C(═O)—, —O—C(═O)—O—, —C(═O)—NH—, —NH—, —NH—C(═NH)— (H may besubstituted with a substituent such as an alkyl group or an acyl group),—S—, —S(═O)₂—, —S(═O)₂—O—, and a group represented by general formula—Y²—O—Y²²—, —Y²¹—O—, —Y²¹—C(═O)—O—, —C(═O)—O—Y²¹—, —[Y²¹—C(═O)—O]m,—Y²²—, —Y²¹—O—C(═O)—Y²²— or —Y²¹—S(═O)₂—O—Y²²— [in the formulae, Y²¹ andY²² each independently represents a divalent hydrocarbon group which mayhave a substituent, O represents an oxygen atom, and m″ represents aninteger of 0 to 3.

In the case where the divalent linking group containing a hetero atom is—C(═O)—NH—, —C(═O)—NH—C(═O)—, —NH— or —NH—C(═NH)—, H may be substitutedwith a substituent such as an alkyl group, an acyl group or the like.The substituent (an alkyl group, an acyl group or the like) preferablyhas 1 to 10 carbon atoms, more preferably 1 to 8, and most preferably 1to 5.

In general formulae —Y²¹—, —O—Y²²— —Y²¹—O—, —Y²¹—C(═O)—O—,—C(═O)—O—Y²¹—, —[Y²¹—C(═O)—O]_(m), —Y²²—, —Y²¹—O—C(═O)—Y²²— or—Y²¹—S(═O)₂—O—Y²²—, Y²¹ and Y²² each independently represents a divalenthydrocarbon group which may have a substituent. Examples of the divalenthydrocarbon group include the same groups as those described above asthe “divalent hydrocarbon group which may have a substituent” in theexplanation of the aforementioned divalent linking group for Ya²¹.

As Y²¹, a linear aliphatic hydrocarbon group is preferable, morepreferably a linear alkylene group, still more preferably a linearalkylene group of 1 to 5 carbon atoms, and a methylene group or anethylene group is particularly desirable.

As Y²², a linear or branched aliphatic hydrocarbon group is preferable,and a methylene group, an ethylene group or an alkylmethylene group ismore preferable. The alkyl group within the alkylmethylene group ispreferably a linear alkyl group of 1 to 5 carbon atoms, more preferablya linear alkyl group of 1 to 3 carbon atoms, and most preferably amethyl group.

In the group represented by the formula —[Y²¹—C(═O)—O]m″—Y²²—, m″represents an integer of 0 to 3, preferably an integer of 0 to 2, morepreferably 0 or 1, and most preferably 1. Namely, it is particularlydesirable that the group represented by the formula—[Y²¹—C(═O)—O]_(m)″-Y²²— is a group represented by the formula—Y²¹—C(═O)—O—Y²²—. Among these, a group represented by the formula—(CH₂)_(a′)—C(═O)—O—(CH₂)_(b′)— is preferable. In the formula, a′ is aninteger of 1 to 10, preferably an integer of 1 to 8, more preferably aninteger of 1 to 5, still more preferably 1 or 2, and most preferably 1.b′ is an integer of 1 to 10, preferably an integer of 1 to 8, morepreferably an integer of 1 to 5, still more preferably 1 or 2, and mostpreferably 1.

Among these examples, as Ya²¹, a single bond, an ester bond [—C(═O)—O—],an ether bond (—O—), a linear or branched alkylene group, or acombination thereof is preferable.

In the formula (a2-1), Ra²¹ represents a lactone-containing cyclicgroup, an —SO₂-containing cyclic group or a carbonate-containing cyclicgroup.

Preferable examples of the lactone-containing cyclic group, the —SO₂—containing cyclic group and the carbonate-containing cyclic group forRa²¹ include groups represented by general formulae (a2-r-1) to(a2-r-7), groups represented by general formulae (a5-r-1) to (a5-r-4)and groups represented by general formulae (ax3-r-1) to (ax3-r-3).

Among the above examples, a lactone-containing cyclic group or a—SO₂-containing cyclic group is preferable, and a group represented bygeneral formula (a2-r-1), (a2-r-2), (a2-r-6) or (a5-r-1) is morepreferable. Specifically, a group represented by any of chemicalformulae (r-1c-1-1) to (r-1c-1-7), (r-1c-2-1) to (r-1c-2-18),(r-1c-6-1), (r-s1-1-1) and (r-s1-1-18) is still more preferable.

As the structural unit (a2) contained in the component (A1), 1 kind ofstructural unit may be used, or 2 or more kinds may be used.

Structural Unit (a3):

The component (A1) may have a structural unit (a3) containing a polargroup-containing aliphatic hydrocarbon group (provided that thestructural units that fall under the definition of structural units (a1)and (a2) are excluded). When the component (A1) includes the structuralunit (a3), the hydrophilicity of the component (A1) is enhanced, therebycontributing to improvement in resolution. Further, the acid diffusionlength may be appropriately adjusted.

Examples of the polar group include a hydroxyl group, cyano group,carboxyl group, or hydroxyalkyl group in which part of the hydrogenatoms of the alkyl group have been substituted with fluorine atoms,although a hydroxyl group is particularly desirable.

Examples of the aliphatic hydrocarbon group include linear or branchedhydrocarbon groups (preferably alkylene groups) of 1 to 10 carbon atoms,and alicyclic hydrocarbon groups (cyclic groups). These cyclic groupscan be selected appropriately from the multitude of groups that havebeen proposed for the resins of resist compositions designed for usewith ArF excimer lasers.

In the case where the cyclic group is a monocyclic group, the monocyclicgroup preferably has 3 to 10 carbon atoms. Of the various possibilities,structural units derived from an acrylate ester that include analiphatic monocyclic group that contains a hydroxyl group, cyano group,carboxyl group or a hydroxyalkyl group in which part of the hydrogenatoms of the alkyl group have been substituted with fluorine atoms areparticularly desirable. Examples of the monocyclic groups include groupsin which two or more hydrogen atoms have been removed from amonocycloalkane. Specific examples include groups in which two or morehydrogen atoms have been removed from a monocycloalkane such ascyclopentane, cyclohexane or cyclooctane. Of these polycyclic groups,groups in which two or more hydrogen atoms have been removed fromcyclopentane or cyclohexane are preferred industrially.

In the case where the cyclic group is a polycyclic group, the polycyclicgroup preferably has 7 to 30 carbon atoms. Of the various possibilities,structural units derived from an acrylate ester that include analiphatic polycyclic group that contains a hydroxyl group, cyano group,carboxyl group or a hydroxyalkyl group in which part of the hydrogenatoms of the alkyl group have been substituted with fluorine atoms areparticularly desirable. Examples of the polycyclic group include groupsin which two or more hydrogen atoms have been removed from abicycloalkane, tricycloalkane, tetracycloalkane or the like. Specificexamples include groups in which two or more hydrogen atoms have beenremoved from a polycycloalkane such as adamantane, norbornane,isobornane, tricyclodecane or tetracyclododecane. Of these polycyclicgroups, groups in which two or more hydrogen atoms have been removedfrom adamantane, norbomane or tetracyclododecane are preferredindustrially.

As the structural unit (a3), there is no particular limitation as longas it is a structural unit containing a polar group-containing aliphatichydrocarbon group, and an arbitrary structural unit may be used.

The structural unit (a3) is preferably a structural unit derived from anacrylate ester which may have the hydrogen atom bonded to the carbonatom on the α-position substituted with a substituent and contains apolar group-containing aliphatic hydrocarbon group.

When the aliphatic hydrocarbon group within the polar group-containingaliphatic hydrocarbon group is a linear or branched hydrocarbon group of1 to 10 carbon atoms, the structural unit (a3) is preferably astructural unit derived from a hydroxyethyl ester of acrylic acid.

On the other hand, in the structural unit (a3), when the hydrocarbongroup within the polar group-containing aliphatic hydrocarbon group is apolycyclic group, structural units represented by formulas (a3-1),(a3-2), (a3-3) and (a3-4) shown below are preferable.

In the formulas, R is the same as defined above; j is an integer of 1 to3; k is an integer of 1 to 3; t′ is an integer of 1 to 3; 1 is aninteger of 0 to 5; and s is an integer of 1 to 3.

In formula (a3-1), j is preferably 1 or 2, and more preferably 1. When jis 2, it is preferable that the hydroxyl groups be bonded to the 3rd and5th positions of the adamantyl group. When j is 1, it is preferable thatthe hydroxyl group be bonded to the 3rd position of the adamantyl group.j is preferably 1, and it is particularly desirable that the hydroxylgroup be bonded to the 3rd position of the adamantyl group.

In formula (a3-2), k is preferably 1. The cyano group is preferablybonded to the 5th or 6th position of the norbornyl group.

In formula (a3-3), t′ is preferably 1. 1 is preferably 1. s ispreferably 1. Further, it is preferable that a 2-norbornyl group or3-norbornyl group be bonded to the terminal of the carboxy group of theacrylic acid. The fluorinated alkyl alcohol is preferably bonded to the5th or 6th position of the norbornyl group.

In formula (a3-4), t′ is preferably 1 or 2. 1 is preferably 0 or 1. s ispreferably 1. The fluorinated alkyl alcohol is preferably bonded to the3rd or 5th position of the cyclohexyl group.

As the structural unit (a3) contained in the component (A1), 1 type ofstructural unit may be used, or 2 or more types may be used.

Structural Unit (a4):

The component (A1) may further include a structural unit (a4) containingan acid non-dissociable, aliphatic cyclic group.

When the component (A1) includes the structural unit (a4), dry etchingresistance of the resist pattern to be formed is improved. Further, thehydrophobicity of the component (A) is further improved. Increase in thehydrophobicity contributes to improvement in terms of resolution, shapeof the resist pattern and the like, particularly in a solvent developingprocess. An “acid non-dissociable, aliphatic cyclic group” in thestructural unit (a4) refers to a cyclic group which is not dissociatedby the action of the acid (e.g., acid generated from a structural unitwhich generates acid upon exposure or acid generated from the component(B)) upon exposure, and remains in the structural unit.

As the structural unit (a4), a structural unit which contains anon-acid-dissociable aliphatic cyclic group, and is also derived from anacrylate ester is preferable. As the cyclic group, any of the multitudeof conventional polycyclic groups used within the resin component ofresist compositions for ArF excimer lasers or KrF excimer lasers (andparticularly for ArF excimer lasers) can be used.

As the aliphatic polycyclic group, at least one polycyclic groupselected from amongst atricyclodecyl group, adamantyl group,tetracyclododecyl group, isobornyl group, and norbomyl group isparticularly desirable in consideration of industrial availability andthe like. These polycyclic groups may be substituted with a linear orbranched alkyl group of 1 to 5 carbon atoms.

Specific examples of the structural unit (a4) include structural unitsrepresented by general formulae (a4-1) to (a4-7) shown below.

In the formulae, R^(α) is the same as defined above.

As the structural unit (a4) contained in the component (A1), 1 type ofstructural unit may be used, or 2 or more types may be used.

—Structural Unit (St)

The structural unit (st) is a structural unit derived from styrene or astyrene derivative. A “structural unit derived from styrene” refers to astructural unit that is formed by the cleavage of the ethylenic doublebond of styrene. A “structural unit derived from a styrene derivative”refers to a structural unit that is formed by the cleavage of theethylenic double bond of a styrene derivative (provided that structuralunits which fall under the definition of the structural unit (a10) isexcluded).

A “styrene derivative” refers to a compound in which at least part ofthe hydrogen atoms of styrene has been substituted with a substituent.Examples of the styrene derivative include a compound in which thehydrogen at the α-position of styrene has been substituted with asubstituent, a compound in which at least one hydrogen atom on thebenzene ring of styrene has been substituted with a substituent, and acompound in which the hydrogen at the α-position of styrene and at leastone hydrogen atom on the benzene ring of styrene has been substitutedwith a substituent.

Examples of the substituent which substitutes the hydrogen atom at theα-position of styrene include an alkyl group having 1 to 5 carbon atoms,and a halogenated alkyl group having 1 to 5 carbon atoms.

The alkyl group of 1 to 5 carbon atoms is preferably a linear orbranched alkyl group of 1 to 5 carbon atoms, and specific examplesinclude a methyl group, an ethyl group, a propyl group, an isopropylgroup, an n-butyl group, an isobutyl group, a tert-butyl group, a pentylgroup, an isopentyl group, and a neopentyl group.

The halogenated alkyl group of 1 to 5 carbon atoms is a group in whichpart or all of the hydrogen atoms of the aforementioned alkyl group of 1to 5 carbon atoms have been substituted with halogen atom(s). As thehalogen atom, a fluorine atom is preferable.

As the substituent which substitutes the hydrogen atom at the α-positionof styrene, an alkyl group having 1 to 5 carbon atoms or a fluorinatedalkyl group having 1 to 5 carbon atoms is preferable, an alkyl grouphaving 1 to 3 carbon atoms or a fluorinated alkyl group having 1 to 3carbon atoms is more preferable, and in terms of industrialavailability, a methyl group is more preferable.

Examples of the substituent which substitutes a hydrogen atom on thebenzene ring of styrene include an alkyl group, an alkoxy group, ahalogen atom, and a halogenated alkyl group.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and more preferably a methyl group, an ethyl group, apropyl group, an n-butyl group or a tert-butyl group.

The alkoxy group as the substituent is preferably an alkoxy group having1 to 5 carbon atoms, more preferably a methoxy group, ethoxy group,n-propoxy group, iso-propoxy group, n-butoxy group or tert-butoxy group,and still more preferably a methoxy group or an ethoxy group.

The halogen atom as the substituent is preferably a fluorine atom.

Examples of the halogenated alkyl group for the substituent includegroups in which part or all of the hydrogen atoms within theaforementioned alkyl groups has been substituted with the aforementionedhalogen atoms.

As the substituent which substitutes a hydrogen atom on the benzene ringof styrene, an alkyl group having 1 to 5 carbon atoms is preferable, amethyl group or an ethyl group is more preferable, and a methyl group isstill more preferable.

As the structural unit (st), a structural unit derived from styrene or astructural unit derived from a styrene derivative in which the hydrogenatom at the α-position of styrene has been substituted with an alkylgroup having 1 to 5 carbon atoms or a halogenated alkyl group having 1to 5 carbon atoms is preferable, a structural unit derived from styreneor a structural unit derived from a styrene derivative in which thehydrogen atom at the α>-position of styrene has been substituted with amethyl group is more preferable, and a structural unit derived fromstyrene is still more preferable.

As the structural unit (st) contained in the component (A1), 1 kind ofstructural unit may be used, or 2 or more kinds of structural units maybe used.

In the resist composition, as the component (A1), one kind of compoundmay be used, or two or more kinds of compounds may be used incombination.

In the resist composition according to the present embodiment, examplesof the component (A1) include a polymeric compound (A10) (hereafter,sometimes referred to as “component (A10)”) having a repeating structureof a structural unit (a01), a structural unit (a02) and a structuralunit (a03); and a mixed resin of a polymeric compound (A11) (hereafter,sometimes referred to as “component (A11)”) having a repeating structureof a structural unit (a01) and a structural unit (a02) and a polymericcompound (A12) (hereafter, sometimes referred to as “component (A12)”)having a repeating structure of a structural unit (a01) and a structuralunit (a03). In the resist composition of the present embodiment, interms of ease in synthesis, the component (A1) is preferably a mixedresin of the component (A1 and the component (A12).

The weight ratio of the component (A11) to the component (A12)(component (A11)

/component (A12)) is preferably 2/8 to 8/2, more preferably 3/7 to 7/3,and still more preferably 4/6 to 6/4.

In the component (A11), the molar ratio of the structural unit (a01) tothe structural unit (a02) (structural unit (a01)/structural unit (a02))is preferably 2/8 to 8/2, more preferably 3/7 to 7/3, and still morepreferably 4/6 to 6/4. The weight average molecular weight (Mw) (thepolystyrene equivalent value determined by gel permeation chromatography(GPC)) of the component (A11) is not particularly limited, but ispreferably 1,000 to 50,000, more preferably 2,000 to 30,000, and stillmore preferably 3,000 to 20,000.

When the Mw of the component (A11) is no more than the upper limit ofthe above-mentioned preferable range, the resist composition exhibits asatisfactory solubility in a resist solvent. On the other hand, when theMw of the component (A11) is at least as large as the lower limit of theabove-mentioned preferable range, dry etching resistance and thecross-sectional shape of the resist pattern becomes satisfactory.

The dispersity (Mw/Mn) of the component (A11) is not particularlylimited, but is preferably 1.0 to 4.0, more preferably 1.0 to 3.0, andmost preferably 1.0 to 2.0. Here, Mn is the number average molecularweight.

In the component (A12), the molar ratio of the structural unit (a01) tothe structural unit (a03) (structural unit (a01)/structural unit (a03))is preferably 2/8 to 8/2, more preferably 3/7 to 7/3, and still morepreferably 4/6 to 6/4. The weight average molecular weight (Mw) (thepolystyrene equivalent value determined by gel permeation chromatography(GPC)) of the component (A12) is not particularly limited, but ispreferably 1,000 to 50,000, more preferably 2,000 to 30,000, and stillmore preferably 3,000 to 20,000.

When the Mw of the component (A12) is no more than the upper limit ofthe above-mentioned preferable range, the resist composition exhibits asatisfactory solubility in a resist solvent. On the other hand, when theMw of the component (A12) is at least as large as the lower limit of theabove-mentioned preferable range, dry etching resistance and thecross-sectional shape of the resist pattern becomes satisfactory.

The dispersity (Mw/Mn) of the component (A12) is not particularlylimited, but is preferably 1.0 to 4.0, more preferably 1.0 to 3.0, andmost preferably 1.0 to 2.0. Here, Mn is the number average molecularweight.

The component (A1) may be produced, for example, by dissolving themonomers for obtaining each of the structural units in a polymerizationsolvent, followed by addition of a radical polymerization initiator suchas azobisisobutyronitrile (AIBN) or dimethyl-2,2′-azobisisoutyrate(e.g., V-601). In the polymerization, a chain transfer agent such asHS—CH₂—CH₂—CH₂—C(CF₃)₂—OH may be used to introduce a —C(CF₃)₂—OH groupat the terminal(s) of the polymer. Such a copolymer having introduced ahydroxyalkyl group in which some of the hydrogen atoms of the alkylgroup are substituted with fluorine atoms is effective in reducingdeveloping defects and LER (line edge roughness: unevenness of the sidewalls of a line pattern).

The weight average molecular weight (Mw) (the polystyrene equivalentvalue determined by gel permeation chromatography (GPC)) of thecomponent (A1) is not particularly limited, but is preferably 1,000 to50,000, more preferably 2,000 to 30,000, and still more preferably 3,000to 20,000.

When the Mw of the component (A1) is no more than the upper limit of theabove-mentioned preferable range, the resist composition exhibits asatisfactory solubility in a resist solvent. On the other hand, when theMw of the component (A1) is at least as large as the lower limit of theabove-mentioned preferable range, dry etching resistance and thecross-sectional shape of the resist pattern becomes satisfactory.

The dispersity (Mw/Mn) of the component (A1) is not particularlylimited, but is preferably 1.0 to 4.0, more preferably 1.0 to 3.0, andmost preferably 1.0 to 2.0. Here, Mn is the number average molecularweight.

—Component (A2)

In the resist composition of the present embodiment, as the component(A), “a base component which exhibits changed solubility in a developingsolution under action of acid” other than the component (A1) (hereafter,referred to as “component (A2)”) may be used in combination.

As the component (A2), there is no particular limitation, and any of themultitude of conventional base resins used within chemically amplifiedresist compositions may be arbitrarily selected for use.

As the component (A2), one kind of a polymer or a low molecular weightcompound may be used, or a combination of two or more kinds may be used.

In the component (A), the amount of the component (A1) based on thetotal weight of the component (A) is preferably 25% by weight or more,more preferably 50% by weight or more, still more preferably 75% byweight or more, and may be even 100% by weight. When the amount of thecomponent (A1) is 25% by weight or more, a resist pattern with improvedlithography properties such as improvement in roughness may be reliablyformed.

In the resist composition of the present embodiment, the amount of thecomponent (A) may be appropriately adjusted depending on the thicknessof the resist film to be formed, and the like.

<Other Components>

The resist composition of the present embodiment may contain, inaddition to the aforementioned component (A), any other optionalcomponents. Examples of the other components include the component (B),the component (D), the component (E), the component (F) and thecomponent (S) described below.

<<Acid-Generator Component (B)>>

The resist composition of the present embodiment may include, inaddition to the component (A), an acid-generator component (hereafter,sometimes referred to as “component (B)”).

As the component (B), there is no particular limitation, and any of theknown acid generators used in conventional chemically amplified resistcompositions may be used.

Examples of these acid generators are numerous, and include onium saltacid generators such as iodonium salts and sulfonium salts; oximesulfonate acid generators; diazomethane acid generators such as bisalkylor bisaryl sulfonyl diazomethanes and poly(bis-sulfonyl)diazomethanes;nitrobenzylsulfonate acid generators; iminosulfonate acid generators;and disulfone acid generators.

As the onium salt acid generator, a compound represented by generalformula (b-1) below (hereafter, sometimes referred to as “component(b-1)”), a compound represented by general formula (b-2) below(hereafter, sometimes referred to as “component (b-2)”) or a compoundrepresented by general formula (b-3) below (hereafter, sometimesreferred to as “component (b-3)”) may be mentioned.

In the formulae, R¹⁰¹ and R¹⁰⁴ to R¹⁰⁸ each independently represents acyclic group which may have a substituent, a chain-like alkyl groupwhich may have a substituent or a chain-like alkenyl group which mayhave a substituent, provided that R¹⁰⁴ and R¹⁰⁵ may be mutually bondedto form a ring structure; R¹⁰² represents a fluorine atom or afluorinated alkyl group having 1 to 5 carbon atoms; Y¹⁰¹ represents asingle bond or a divalent group containing an oxygen atom; V¹⁰¹ to V¹⁰³each independently represents a single bond, an alkylene group or afluorinated alkylene group; L¹⁰¹ and L¹⁰² each independently representsa single bond or an oxygen atom; L¹⁰³ to L¹⁰⁵ each independentlyrepresents a single bond, —CO— or —SO₂—; m represents an integer of 1 ormore; and M′^(m+) represents an m-valent onium cation.

{Anion Moiety}

—Anion Moiety of Component (b-1)

In the formula (b-1), R¹⁰¹ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent.

Cyclic Group which May have a Substituent:

The cyclic group is preferably a cyclic hydrocarbon group, and thecyclic hydrocarbon group may be either an aromatic hydrocarbon group oran aliphatic hydrocarbon group. An “aliphatic hydrocarbon group” refersto a hydrocarbon group that has no aromaticity. The aliphatichydrocarbon group may be either saturated or unsaturated, but ingeneral, the aliphatic hydrocarbon group is preferably saturated.

The aromatic hydrocarbon group for R¹⁰¹ is a hydrocarbon group having anaromatic ring. The aromatic hydrocarbon ring preferably has 3 to 30carbon atoms, more preferably 5 to 30, still more preferably 5 to 20,still more preferably 6 to 15, and most preferably 6 to 10. Here, thenumber of carbon atoms within a substituent(s) is not included in thenumber of carbon atoms of the aromatic hydrocarbon group.

Examples of the aromatic ring contained in the aromatic hydrocarbongroup represented by R¹⁰¹ include benzene, fluorene, naphthalene,anthracene, phenanthrene and biphenyl; and aromatic hetero rings inwhich part of the carbon atoms constituting the aforementioned aromaticrings has been substituted with a hetero atom. Examples of the heteroatom within the aromatic hetero rings include an oxygen atom, a sulfuratom and a nitrogen atom.

Specific examples of the aromatic hydrocarbon group represented by R¹⁰¹include a group in which one hydrogen atom has been removed from theaforementioned aromatic ring (i.e., an aryl group, such as a phenylgroup or a naphthyl group), and a group in which one hydrogen of theaforementioned aromatic ring has been substituted with an alkylene group(e.g., an arylalkyl group such as a benzyl group, a phenethyl group, a1-naphthylmethyl group, a 2-naphthylmethyl group, a 1-naphthylethylgroup or a 2-naphthylethyl group). The alkylene group (alkyl chainwithin the arylalkyl group) preferably has 1 to 4 carbon atom, morepreferably 1 or 2, and most preferably 1.

Examples of the cyclic aliphatic hydrocarbon group for R¹⁰¹ includealiphatic hydrocarbon groups containing a ring in the structure thereof.

As examples of the hydrocarbon group containing a ring in the structurethereof, an alicyclic hydrocarbon group (a group in which one hydrogenatom has been removed from an aliphatic hydrocarbon ring), a group inwhich the alicyclic hydrocarbon group is bonded to the terminal of theaforementioned chain-like aliphatic hydrocarbon group, and a group inwhich the alicyclic group is interposed within the aforementioned linearor branched aliphatic hydrocarbon group, can be given.

The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms, andmore preferably 3 to 12 carbon atoms.

The alicyclic hydrocarbon group may be either a polycyclic group or amonocyclic group. As the monocyclic alicyclic hydrocarbon group, a groupin which one or more hydrogen atoms have been removed from amonocycloalkane is preferable. The monocycloalkane preferably has 3 to 6carbon atoms, and specific examples thereof include cyclopentane andcyclohexane. As the polycyclic alicyclic hydrocarbon group, a group inwhich one or more hydrogen atoms have been removed from apolycycloalkane is preferable, and the polycyclic group preferably has 7to 30 carbon atoms. Among polycycloalkanes, a polycycloalkane having abridged ring polycyclic skeleton, such as adamantane, norbornane,isobornane, tricyclodecane or tetracyclodpdecane, and a polycycloalkanehaving a condensed ring polycyclic skeleton, such as a cyclic grouphaving a steroid skeleton are preferable.

Among these examples, as the cyclic aliphatic hydrocarbon group forR¹⁰¹, a group in which one or more hydrogen atoms have been removed froma monocycloalkane or a polycycloalkane is preferable, a group in whichone or more hydrogen atoms have been removed from a polycycloalkane ismore preferable, an adamantyl group or a norbornyl group is still morepreferable, and an adamantyl group is most preferable.

The linear aliphatic hydrocarbon group which may be bonded to thealicyclic hydrocarbon group preferably has 1 to 10 carbon atoms, morepreferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbonatoms, and most preferably 1 to 3 carbon atoms. As the linear aliphatichydrocarbon group, a linear alkylene group is preferable. Specificexamples thereof include a methylene group [—CH₂—], an ethylene group[—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], a tetramethylene group[—(CH₂)₄-] and a pentamethylene group [—(CH₂)₅—].

The branched aliphatic hydrocarbon group which may be bonded to thealicyclic hydrocarbon group preferably has 2 to 10 carbon atoms, morepreferably 3 to 6 carbon atoms, still more preferably 3 or 4 carbonatoms, and most preferably 3 carbon atoms. As the branched aliphatichydrocarbon group, branched alkylene groups are preferred, and specificexamples include various alkylalkylene groups, including alkylmethylenegroups such as —CH(CH₃)—, —CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—,—C(CH₃)(CH₂CH₂CH₃)—, and —C(CH₂CH₃)₂—; alkylethylene groups such as—CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂—, —CH(CH₂CH₃)CH₂—, and—C(CH₂CH₃)₂—CH₂—; alkyltrimethylene groups such as —CH(CH₃)CH₂CH₂—, and—CH₂CH(CH₃)CH₂—; and alkyltetramethylene groups such as—CH(CH₃)CH₂CH₂CH₂—, and —CH₂CH(CH₃)CH₂CH₂—. As the alkyl group withinthe alkylalkylene group, a linear alkyl group of 1 to 5 carbon atoms ispreferable.

The cyclic hydrocarbon group for R¹⁰¹ may contain a hetero atom such asa heterocycle. Specific examples include lactone-containing cyclicgroups represented by the aforementioned general formulae (a2-r-1) to(a2-r-7), the —SO₂— containing cyclic group represented by theaforementioned formulae (a5-r-1) to (a5-r-4), and other heterocyclicgroups represented by chemical formulae (r-hr-1) to (r-hr-16) shownbelow. In the formulae, * indicates the bonding site which bonds to Y¹⁰¹in formula (b-1).

As the substituent for the cyclic group for R¹⁰¹, an alkyl group, analkoxy group, a halogen atom, a halogenated alkyl group, a hydroxylgroup, a carbonyl group, a nitro group or the like can be used. Thealkyl group as the substituent is preferably an alkyl group of 1 to 5carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is particularly desirable.

The alkoxy group as the substituent is preferably an alkoxy group having1 to 5 carbon atoms, more preferably a methoxy group, ethoxy group,n-propoxy group, iso-propoxy group, n-butoxy group or tert-butoxy group,and most preferably a methoxy group or an ethoxy group.

Examples of the halogen atom for the substituent include a fluorineatom, a chlorine atom, a bromine atom and an iodine atom, and a fluorineatom is preferable.

Example of the aforementioned halogenated alkyl group includes a groupin which a part or all of the hydrogen atoms within an alkyl group of 1to 5 carbon atoms (e.g., a methyl group, an ethyl group, a propyl group,an n-butyl group or a tert-butyl group) have been substituted with theaforementioned halogen atoms.

The carbonyl group as the substituent is a group that substitutes amethylene group (—CH₂—) constituting the cyclic hydrocarbon group.

The cyclic hydrocarbon group for R¹⁰¹ may be a condensed cyclic group inwhich an aliphatic hydrocarbon ring and an aromatic hydrocarbon ring arefused. Examples of the condensed ring include a compound in which one ormore aromatic rings are fused with a polycycloalkane having a bridgedpolycyclic skeleton. Specific examples of the bridged polycycloalkaneinclude a bicycloalkane, such as bicyclo[2.2.1]heptane (norbornane) orbicyclo[2.2.2]octane. As the condensed cyclic group, a group containinga condensed ring in which 2 or 3 aromatic rings are fused with abicycloalkane is preferable, and a group containing a condensed ring inwhich 2 or 3 aromatic rings are fused with bicyclo[2.2.2]octane is morepreferable. Specific examples of the condensed cyclic group for R¹⁰¹include groups represented by formulae (r-br-1) and (r-br-2) shownbelow. In the formulae, * indicates the bonding site which bonds to Y¹⁰¹in formula (b-1).

As the substituent for the condensed cyclic group for R¹⁰¹, an alkylgroup, an alkoxy group, a halogen atom, a halogenated alkyl group, ahydroxy group, a carbonyl group, a nitro group, an aromatic hydrocarbongroup or an alicyclic hydrocarbon group may be mentioned.

The alkyl group, the alkoxy group, the halogen atom and the halogenatedalkyl group as the substituent for the condensed cyclic group are thesame as defined for the substituents for the cyclic group represented byR¹¹.

Examples of the aromatic hydrocarbon group as the substituent for thecondensed cyclic group include a group in which one hydrogen atom hasbeen removed from an aromatic hydrocarbon ring (an aryl group, such as aphenyl group or a naphthyl group); a group in which one hydrogen atom ofthe aforementioned aromatic hydrocarbon ring has been substituted withan alkylene group (an arylalkyl group such as a benzyl group, aphenethyl group, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a1-naphthylethyl group, or a 2-naphthylethyl group); and a heterocyclicgroup represented by any of the aforementioned formulae (r-hr-1) to(r-hr-6).

Examples of the alicyclic hydrocarbon group as the substituent for thecondensed cyclic group include a group in which one hydrogen atom hasbeen removed from a monocycloalkane such as cyclopentane or cyclohexane;a group in which one hydrogen atom has been removed from apolycycloalkane such as adamantane, norbomane, isobornane,tricyclodecane or tetracyclododecane; a lactone-containing cyclic grouprepresented by any of the aforementioned general formulae (a2-r-1) to(a2-r-7); an —SO₂-containing cyclic group represented by any of theaforementioned general formulae (a5-r-1) to (a5-r-4); and a heterocyclicgroup represented by any of the aforementioned formulae (r-hr-7) to(r-hr-16).

Chain alkyl group which may have a substituent:

The chain-like alkyl group for R¹⁰¹ may be linear or branched.

The linear alkyl group preferably has 1 to 20 carbon atoms, morepreferably 1 to 15, and most preferably 1 to 10.

The branched alkyl group preferably has 3 to 20 carbon atoms, morepreferably 3 to 15, and most preferably 3 to 10. Specific examplesinclude a 1-methylethyl group, a 1-methylpropyl group, a 2-methylpropylgroup, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutylgroup, a 1-ethylbutyl group, a 2-ethylbutyl group, a 1-methylpentylgroup, a 2-methylpentyl group, a 3-methylpentyl group and a4-methylpentyl group.

Chain Alkenyl Group which May have a Substituent:

The chain-like alkenyl group for R¹⁰¹ may be linear or branched, andpreferably has 2 to 10 carbon atoms, more preferably 2 to 5 carbonatoms, still more preferably 2 to 4 carbon atoms, and most preferably 3carbon atoms. Examples of linear alkenyl groups include a vinyl group, apropenyl group (an allyl group) and a butynyl group. Examples ofbranched alkenyl groups include a 1-methylvinyl group, a 2-methylvinylgroup, a 1-methylpropenyl group and a 2-methylpropenyl group.

Among these examples, as the chain-like alkenyl group, a linear alkenylgroup is preferable, a vinyl group or a propenyl group is morepreferable, and a vinyl group is most preferable.

As the substituent for the chain-like alkyl group or alkenyl group forR¹⁰¹, an alkoxy group, a halogen atom, a halogenated alkyl group, ahydroxyl group, a carbonyl group, a nitro group, an amino group, acyclic group for R¹⁰¹ or the like can be used.

Among the above examples, as R¹¹, a cyclic group which may have asubstituent is preferable, and a cyclic hydrocarbon group which may havea substituent is more preferable. Specifically, a phenyl group, anaphthyl group, a group in which one or more hydrogen atoms have beenremoved from a polycycloalkane, a lactone-containing cyclic grouprepresented by any one of the aforementioned formula (a2-r-1) to(a2-r-7), and an —SO₂— containing cyclic group represented by any one ofthe aforementioned formula (a5-r-1) to (a5-r-4).

In formula (b-1), Y¹⁰ represents a single bond or a divalent linkinggroup containing an oxygen atom.

In the case where Y¹⁰¹ is a divalent linking group containing an oxygenatom, Y¹⁰ may contain an atom other than an oxygen atom. Examples ofatoms other than an oxygen atom include a carbon atom, a hydrogen atom,a sulfur atom and a nitrogen atom.

Examples of divalent linking groups containing an oxygen atom includenon-hydrocarbon, oxygen atom-containing linking groups such as an oxygenatom (an ether bond; —O—), an ester bond (—C(═O)—O—), an oxycarbonylgroup (—O—C(═O)—), an amido bond (—C(═O)—NH—), a carbonyl group(—C(═O)—) and a carbonate bond (—O—C(═O)—O—); and combinations of theaforementioned non-hydrocarbon, hetero atom-containing linking groupswith an alkylene group. Furthermore, the combinations may have asulfonyl group (—SO₂—) bonded thereto. Examples of the divalent linkinggroup containing an oxygen atom include divalent linking groupsrepresented by general formula (y-a1-1) to (y-a1-7) shown below.

In the formulae, V′¹⁰¹ represents a single bond or an alkylene group of1 to 5 carbon atoms; V′¹⁰² represents a divalent saturated hydrocarbongroup of 1 to 30 carbon atoms.

The divalent saturated hydrocarbon group for V′¹⁰² is preferably analkylene group of 1 to 30 carbon atoms, more preferably an alkylenegroup of 1 to 10 carbon atoms, and still more preferably an alkylenegroup of 1 to 5 carbon atoms.

The alkylene group for V′¹⁰¹ and V′¹⁰² may be a linear alkylene group ora branched alkylene group, and a linear alkylene group is preferable.

Specific examples of the alkylene group for V′¹⁰¹ and V′¹⁰² include amethylene group [—CH₂—]; an alkylmethylene group, such as —CH(CH₃)—,—CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)— and—C(CH₂CH₃)₂—; an ethylene group [—CH₂CH₂—]; an alkylethylene group, suchas —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂— and —CH(CH₂CH₃)CH₂—; atrimethylene group (n-propylene group) [—CH₂CH₂CH₂—]; analkyltrimethylene group, such as —CH(CH₃)CH₂CH₂— and —CH₂CH(CH₃)CH₂—; atetramethylene group [—CH₂CH₂CH₂CH₂—]; an alkyltetramethylene group,such as —CH(CH₃)CH₂CH₂CH₂—, —CH₂CH(CH₃)CH₂CH₂—; and a pentamethylenegroup [—CH₂CH₂CH₂CH₂CH₂—].

Further, part of methylene group within the alkylene group for V′¹⁰¹ andV′¹⁰² may be substituted with a divalent aliphatic cyclic group of 5 to10 carbon atoms. The aliphatic cyclic group is preferably a divalentgroup in which one hydrogen atom has been removed from the cyclicaliphatic hydrocarbon group (monocyclic aliphatic hydrocarbon group orpolycyclic aliphatic hydrocarbon group) for Ra′³ in the aforementionedformula (a1-r-1), and a cyclohexylene group, 1,5-adamantylene group or2,6-adamantylene group is preferable.

Y¹⁰¹ is preferably a divalent linking group containing an ether bond ora divalent linking group containing an ester bond, and groupsrepresented by the aforementioned formulas (y-a1-1) to (y-a1-5) arepreferable.

In formula (b-1), V¹⁰¹ represents a single bond, an alkylene group or afluorinated alkylene group. The alkylene group and the fluorinatedalkylene group for V¹⁰¹ preferably has 1 to 4 carbon atoms. Examples ofthe fluorinated alkylene group for V¹⁰¹ include a group in which part orall of the hydrogen atoms within the alkylene group for V¹⁰¹ have beensubstituted with fluorine. Among these examples, as V¹⁰¹, a single bondor a fluorinated alkylene group of 1 to 4 carbon atoms is preferable.

In formula (b-1), R¹⁰² represents a fluorine atom or a fluorinated alkylgroup of 1 to 5 carbon atoms. R¹⁰² is preferably a fluorine atom or aperfluoroalkyl group of 1 to 5 carbon atoms, and more preferably afluorine atom.

Specific examples of the anion moiety represented by formula (b-1)include a fluorinated alkylsulfonate anion such as atrifluoromethanesulfonate anion or a perfluorobutanesulfonate anion inthe case where Y¹⁰¹ is a single bond; and an anion represented by anyone of formulae (an-1) to (an-3) in the case where Y¹⁰¹ represents adivalent linking group containing an oxygen atom.

In the formulae, R″¹⁰¹ represents an aliphatic cyclic group which mayhave a substituent, a monovalent heterocyclic group represented by anyof the aforementioned formulae (r-hr-1) to (r-hr-6), a condensed cyclicgroup represented by the aforementioned formula (r-br-1) or (r-br-2), ora chain-like alkyl group which may have a substituent; R″¹⁰² representsan aliphatic cyclic group which may have a substituent, a condensedcyclic group represented by the aforementioned formula (r-br-1) or(r-br-2), a lactone-containing cyclic group represented by any of theaforementioned formulae (a2-r-1) and (a2-r-3) to (a2-r-7), or a—SO₂-containing cyclic group represented by any of formulae (a5-r-1) to(a5-r-4); R″¹⁰³ represents an aromatic cyclic group which may have asubstituent, an aliphatic cyclic group which may have a substituent, ora chain-like alkenyl group which may have a substituent; V″¹⁰¹represents a single bond, an alkylene group having 1 to 4 carbon atomsor a fluorinated alkylene group having 1 to 4 carbon atoms; R¹⁰²represents a fluorine atom or a fluorinated alkyl group of 1 to 5 carbonatoms; each v″ independently represents an integer of 0 to 3; each q″independently represents an integer of 0 to 20; and n″ represents 0 or1.

As the aliphatic cyclic group for R″¹⁰¹, R″¹⁰² and R″¹⁰³ which may havea substituent, the same groups as the cyclic aliphatic hydrocarbon groupfor R¹⁰¹ in the aforementioned formula (b-1) are preferable. Examples ofthe substituent include the same substituents as those described abovefor the cyclic aliphatic hydrocarbon group for R¹⁰¹ in theaforementioned formula (b-1).

As the aromatic cyclic group for R″¹⁰³ which may have a substituent, thesame groups as the aromatic hydrocarbon group for the cyclic hydrocarbongroup represented by R¹⁰¹ in the aforementioned formula (b-1) ispreferable. Examples of the substituent include the same substituents asthose described above for the aromatic hydrocarbon group for R¹⁰¹ in theaforementioned formula (b-1).

As the chain alkyl group for R″¹⁰¹ which may have a substituent, thesame chain alkyl groups as those described above for R¹⁰¹ in theaforementioned formula (b-1) are preferable.

As the chain alkenyl group for R″¹⁰³ which may have a substituent, thesame chain alkenyl groups as those described above for R¹⁰¹ in theaforementioned formula (b-1) are preferable.

—Anion Moiety of Component (b-2)

In formula (b-2), R¹⁰⁴ and R¹⁰⁵ each independently represents a cyclicgroup which may have a substituent, a chain-like alkyl group which mayhave a substituent or a chain-like alkenyl group which may have asubstituent, and is the same as defined for R¹⁰¹ in formula (b-1). R¹⁰⁴and R¹⁰⁵ may be mutually bonded to form a ring.

As R¹⁰⁴ and R¹⁰⁵, a chain-like alkyl group which may have a substituentis preferable, and a linear or branched alkyl group or a linear orbranched fluorinated alkyl group is more preferable.

The chain-like alkyl group preferably has 1 to 10 carbon atoms, morepreferably 1 to 7 carbon atoms, and still more preferably 1 to 3 carbonatoms. The smaller the number of carbon atoms of the chain-like alkylgroup for R¹⁰⁴ and R¹⁵, the more the solubility in a resist solvent isimproved. Further, in the chain alkyl group for R¹⁰⁴ and R¹⁰⁵, thelarger the number of hydrogen atoms being substituted with fluorineatom(s), the acid strength becomes stronger, and the transparency to ahigh energy beam having a wavelength of no more than 250 nm or electronbeam may be improved. The fluorination ratio of the chain-like alkylgroup is preferably from 70 to 100%, more preferably from 90 to 100%,and it is particularly desirable that the chain-like alkyl group be aperfluoroalkyl group in which all hydrogen atoms are substituted withfluorine atoms.

In formula (b-2), V¹⁰² and V¹⁰³ each independently represents a singlebond, an alkylene group or a fluorinated alkylene group, and is the sameas defined for V¹⁰¹ in formula (b-1).

In formula (b-2), L¹⁰¹ and L¹⁰² each independently represents a singlebond or an oxygen atom.

—Anion Moiety of Component (b-3)

In formula (b-3), R¹⁰⁶ to R¹⁰⁸ each independently represents a cyclicgroup which may have a substituent, a chain-like alkyl group which mayhave a substituent or a chain-like alkenyl group which may have asubstituent, and is the same as defined for R¹⁰¹ in formula (b-1).

In formula (b-3), L¹⁰³ to L¹⁰⁵ each independently represents a singlebond, —CO— or —SO₂—.

Among these examples, as the anion moiety of the component (B), an anionfor the component (b-1) is preferable. Among these, an anion representedby any one of the aforementioned general formulae (an-1) to (an-3) ismore preferable, and an anion represented by the aforementioned generalformula (an-1) or (an-2) is more preferable, and an anion represented bythe aforementioned general formula (an-2) is still more preferable.

{Cation Moiety}

In formulae (b-1), (b-2) and (b-3), M′^(m+) represents an m-valent oniumcation. Among these, a sulfonium cation or a iodonium cation ispreferable. m represents an integer of 1 or more.

Preferable examples of the cation moiety ((M′^(m+))_(1/m)) include anorganic cation represented by any of general formulae (ca-1) to (ca-5)shown below.

In the formulae, R²⁰¹ to R²⁰⁷, R²¹¹ and R²¹² each independentlyrepresents an aryl group which may have a substituent, an alkyl groupwhich may have a substituent, or an alkenyl group which may have asubstituent. R²⁰¹ to R²⁰³, R²⁰⁶ and R²⁰⁷, and R²¹¹ and R²¹² may bemutually bonded to form a ring with the sulfur atom. R²⁰ and R²⁰⁹ eachindependently represents a hydrogen atom or an alkyl group of 1 to 5carbon atoms. R²¹⁰ represents an aryl group which may have asubstituent, an alkyl group which may have a substituent, an alkenylgroup which may have a substituent, or an —SO₂— containing cyclic groupwhich may have a substituent. L²⁰¹ represents —C(═O)— or —C(═O)—O—. EachY²⁰¹ independently represents an arylene group, an alkylene group or analkenylene group. x represents 1 or 2. W²⁰¹ represents an (x+1) valentlinking group.

In formulae (ca-1) to (ca-5), as the aryl group for R²⁰¹ to R²⁰⁷, R²¹¹and R²¹², an unsubstituted aryl group of 6 to 20 carbon atoms can bementioned, and a phenyl group or a naphthyl group is preferable.

The alkyl group for R²⁰¹ to R²⁰⁷, R²¹¹ and R²¹² is preferably achain-like or cyclic alkyl group having 1 to 30 carbon atoms.

The alkenyl group for R²⁰¹ to R²⁰⁷, R²¹¹ and R²¹² preferably has 2 to 10carbon atoms.

Specific examples of the substituent which R²⁰¹ to R²⁰⁷ and R²¹⁰ to R²¹²may have include an alkyl group, a halogen atom, a halogenated alkylgroup, a carbonyl group, a cyano group, an amino group, an aryl group,and groups represented by general formulae (ca-r-1) to (ca-r-7) shownbelow.

In the formulae, each R′²⁰¹ independently represents a hydrogen atom, acyclic group which may have a substituent, a chain-like alkyl groupwhich may have a substituent, or a chain-like alkenyl group which mayhave a substituent.

Cyclic Group which May have a Substituent:

The cyclic group is preferably a cyclic hydrocarbon group, and thecyclic hydrocarbon group may be either an aromatic hydrocarbon group oran aliphatic hydrocarbon group. An “aliphatic hydrocarbon group” refersto a hydrocarbon group that has no aromaticity. The aliphatichydrocarbon group may be either saturated or unsaturated, but ingeneral, the aliphatic hydrocarbon group is preferably saturated.

The aromatic hydrocarbon group for R′²⁰¹ is a hydrocarbon group havingan aromatic ring. The aromatic hydrocarbon group preferably has 3 to 30carbon atoms, more preferably 5 to 30 carbon atoms, still morepreferably 5 to 20 carbon atoms, still more preferably 6 to 15 carbonatoms, and most preferably 6 to 10 carbon atoms. Here, the number ofcarbon atoms within a substituent(s) is not included in the number ofcarbon atoms of the aromatic hydrocarbon group.

Examples of the aromatic ring contained in the aromatic hydrocarbongroup for R′²⁰¹ include benzene, fluorene, naphthalene, anthracene,phenanthrene, biphenyl, or an aromatic hetero ring in which part of thecarbon atoms constituting the aromatic ring has been substituted with ahetero atom. Examples of the hetero atom within the aromatic heterorings include an oxygen atom, a sulfur atom and a nitrogen atom.

Specific examples of the aromatic hydrocarbon group for R′²⁰¹ include agroup in which 1 hydrogen atom has been removed from the aforementionedaromatic ring (an aryl group, such as a phenyl group or a naphthylgroup), and a group in which 1 hydrogen atom of the aforementionedaromatic ring has been substituted with an alkylene group (an arylalkylgroup, such as a benzyl group, a phenethyl group, a 1-naphthylmethylgroup, a 2-naphthylmethyl group, a 1-naphthylethyl group, or a2-naphthylethyl group). The alkylene group (alkyl chain within thearylalkyl group) preferably has 1 to 4 carbon atom, more preferably 1 or2, and most preferably 1.

Examples of the cyclic aliphatic hydrocarbon group for R′²⁰¹ includealiphatic hydrocarbon groups containing a ring in the structure thereof.

As examples of the hydrocarbon group containing a ring in the structurethereof, an alicyclic hydrocarbon group (a group in which one hydrogenatom has been removed from an aliphatic hydrocarbon ring), a group inwhich the alicyclic hydrocarbon group is bonded to the terminal of theaforementioned chain-like aliphatic hydrocarbon group, and a group inwhich the alicyclic group is interposed within the aforementioned linearor branched aliphatic hydrocarbon group, can be given.

The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms, andmore preferably 3 to 12 carbon atoms.

The alicyclic hydrocarbon group may be either a polycyclic group or amonocyclic group. As the monocyclic alicyclic hydrocarbon group, a groupin which one or more hydrogen atoms have been removed from amonocycloalkane is preferable. The monocycloalkane preferably has 3 to 6carbon atoms, and specific examples thereof include cyclopentane andcyclohexane. As the polycyclic alicyclic hydrocarbon group, a group inwhich one or more hydrogen atoms have been removed from apolycycloalkane is preferable, and the polycyclic group preferably has 7to 30 carbon atoms. Among polycycloalkanes, a polycycloalkane having abridged ring polycyclic skeleton, such as adamantane, norbornane,isobornane, tricyclodecane or tetracyclodpdecane, and a polycycloalkanehaving a condensed ring polycyclic skeleton, such as a cyclic grouphaving a steroid skeleton are preferable.

Among these examples, as the cyclic aliphatic hydrocarbon group forR′²⁰¹, a group in which one or more hydrogen atoms have been removedfrom a monocycloalkane or a polycycloalkane is preferable, a group inwhich one or more hydrogen atoms have been removed from apolycycloalkane is more preferable, an adamantyl group or a norbornylgroup is still more preferable, and an adamantyl group is mostpreferable.

The linear or branched aliphatic hydrocarbon group which may be bondedto the alicyclic hydrocarbon group preferably has 1 to 10 carbon atoms,more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbonatoms, and most preferably 1 to 3 carbon atoms.

As the linear aliphatic hydrocarbon group, a linear alkylene group ispreferable. Specific examples thereof include a methylene group [—CH₂—],an ethylene group [—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], atetramethylene group [—(CH₂)₄-] and a pentamethylene group [—(CH₂)₅—].

As the branched aliphatic hydrocarbon group, branched alkylene groupsare preferred, and specific examples include various alkylalkylenegroups, including alkylmethylene groups such as —CH(CH₃)—, —CH(CH₂CH₃)—,—C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)—, and —C(CH₂CH₃)₂—;alkylethylene groups such as —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—,—C(CH₃)₂CH₂—, —CH(CH₂CH₃)CH₂—, and —C(CH₂CH₃)₂—CH₂—; alkyltrimethylenegroups such as —CH(CH₃)CH₂CH₂—, and —CH₂CH(CH₃)CH₂—; andalkyltetramethylene groups such as —CH(CH₃)CH₂CH₂CH₂—, and—CH₂CH(CH₃)CH₂CH₂—. As the alkyl group within the alkylalkylene group, alinear alkyl group of 1 to 5 carbon atoms is preferable.

The cyclic hydrocarbon group for R′²⁰¹ may contain a hetero atom such asa heterocycle. Specific examples include lactone-containing cyclicgroups represented by the aforementioned general formulae (a2-r-1) to(a2-r-7), the —SO₂— containing cyclic group represented by theaforementioned formulae (a5-r-1) to (a5-r-4), and other heterocyclicgroups represented by the aforementioned chemical formulae (r-hr-1) to(r-hr-16).

As the substituent for the cyclic group for R′²⁰¹, an alkyl group, analkoxy group, a halogen atom, a halogenated alkyl group, a hydroxylgroup, a carbonyl group, a nitro group or the like can be used.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is particularly desirable.

The alkoxy group as the substituent is preferably an alkoxy group having1 to 5 carbon atoms, more preferably a methoxy group, ethoxy group,n-propoxy group, iso-propoxy group, n-butoxy group or tert-butoxy group,and most preferably a methoxy group or an ethoxy group.

The halogen atom as the substituent is preferably a fluorine atom.

Example of the aforementioned halogenated alkyl group includes a groupin which a part or all of the hydrogen atoms within an alkyl group of 1to 5 carbon atoms (e.g., a methyl group, an ethyl group, a propyl group,an n-butyl group or a tert-butyl group) have been substituted with theaforementioned halogen atoms.

The carbonyl group as the substituent is a group that substitutes amethylene group (—CH₂—) constituting the cyclic hydrocarbon group.

Chain alkyl group which may have a substituent:

The chain alkyl group for R′²⁰¹ may be linear or branched.

The linear alkyl group preferably has 1 to 20 carbon atoms, morepreferably 1 to 15 carbon atoms, and still more preferably 1 to 10carbon atoms.

The branched alkyl group preferably has 3 to 20 carbon atoms, morepreferably 3 to 15 carbon atoms, and still more preferably 3 to 10carbon atoms. Specific examples include a 1-methylethyl group, a1-methylpropyl group, a 2-methylpropyl group, a 1-methylbutyl group, a2-methylbutyl group, a 3-methylbutyl group, a 1-ethylbutyl group, a2-ethylbutyl group, a 1-methylpentyl group, a 2-methylpentyl group, a3-methylpentyl group and a 4-methylpentyl group.

Chain alkenyl group which may have a substituent:

The chain alkenyl group for R′²⁰¹ may be linear or branched, andpreferably has 2 to 10 carbon atoms, more preferably 2 to 5 carbonatoms, still more preferably 2 to 4 carbon atoms, and most preferably 3carbon atoms. Examples of linear alkenyl groups include a vinyl group, apropenyl group (an allyl group) and a butynyl group. Examples ofbranched alkenyl groups include a 1-methylvinyl group, a 2-methylvinylgroup, a 1-methylpropenyl group and a 2-methylpropenyl group.

Among these examples, as the chain-like alkenyl group, a linear alkenylgroup is preferable, a vinyl group or a propenyl group is morepreferable, and a vinyl group is most preferable.

As the substituent for the chain-like alkyl group or alkenyl group forR′²⁰¹, an alkoxy group, a halogen atom, a halogenated alkyl group, ahydroxyl group, a carbonyl group, a nitro group, an amino group, acyclic group for R′²⁰¹ or the like may be used.

As the cyclic group which may have a substituent, the chain alkyl groupwhich may have a substituent and the chain alkenyl group which may havea substituent for R′²⁰¹, the same groups as those described above may bementioned. As the cyclic group which may have a substituent and chainalkyl group which may have a substituent, the same groups as thosedescribed above for the acid dissociable group represented by theaforementioned formula (a1-r-2) may be also mentioned.

Among these examples, as R′²⁰¹, a cyclic group which may have asubstituent is preferable, and a cyclic hydrocarbon group which may havea substituent is more preferable. Specifically, for example, a phenylgroup, a naphthyl group, a group in which one or more hydrogen atomshave been removed from a polycycloalkane, a lactone-containing cyclicgroup represented by any one of the aforementioned formula (a2-r-1) to(a2-r-7), and an —SO₂— containing cyclic group represented by any one ofthe aforementioned formula (a5-r-1) to (a5-r-4) are preferable.

In formulae (ca-1) to (ca-5), in the case where R²⁰¹ to R²⁰³, R²⁰⁶ andR²⁰⁷, or R²¹ and R²¹² are mutually bonded to form a ring with the sulfuratom, these groups may be mutually bonded via a hetero atom such as asulfur atom, an oxygen atom or a nitrogen atom, or a functional groupsuch as a carbonyl group, —SO—, —SO₂—, —SO₃—, —COO—, —CONH— or—N(R_(N))— (R_(N) represents an alkyl group of 1 to 5 carbon atoms). Thering containing the sulfur atom in the skeleton thereof is preferably a3 to 10-membered ring, and most preferably a 5 to 7-membered ring.Specific examples of the ring formed include a thiophene ring, athiazole ring, a benzothiophene ring, a thianthrene ring, abenzothiophene ring, a dibenzothiophene ring, a 9H-thioxanthene ring, athioxanthone ring, a phenoxathiin ring, a tetrahydrothiophenium ring,and a tetrahydrothiopyranium ring.

R²⁰⁸ and R²⁰⁹ each independently represents a hydrogen atom or an alkylgroup of 1 to 5 carbon atoms, preferably a hydrogen atom or an alkylgroup of 1 to 3 carbon atoms, and when R²⁰⁸ and R²⁰⁹ each represents analkyl group, R²⁰⁸ and R²⁰⁹ may be mutually bonded to form a ring.

R²¹⁰ represents an aryl group which may have a substituent, an alkylgroup which may have a substituent, an alkenyl group which may have asubstituent, or an SO₂-containing cyclic group which may have asubstituent.

Examples of the aryl group for R²¹⁰ include an unsubstituted aryl groupof 6 to 20 carbon atoms, and a phenyl group or a naphthyl group ispreferable.

As the alkyl group for R²¹⁰, a chain-like or cyclic alkyl group having 1to 30 carbon atoms is preferable.

The alkenyl group for R²¹⁰ preferably has 2 to 10 carbon atoms. As the—SO₂-containing cyclic group for R²¹⁰ which may have a substituent, an“—SO₂-containing polycyclic group” is preferable, and a grouprepresented by the aforementioned general formula (a5-r-1) is morepreferable.

Each Y²⁰¹ independently represents an arylene group, an alkylene groupor an alkenylene group.

Examples of the arylene group for Y²⁰¹ include groups in which onehydrogen atom has been removed from an aryl group given as an example ofthe aromatic hydrocarbon group for R¹⁰1 in the aforementioned formula(b-1).

Examples of the alkylene group and alkenylene group for Y²⁰¹ includegroups in which one hydrogen atom has been removed from the chain-likealkyl group or the chain-like alkenyl group given as an example of R¹⁰1in the aforementioned formula (b-1).

In the formula (ca-4), x represents 1 or 2.

W²⁰¹ represents a linking group having a valency of (x+1), i.e., adivalent or trivalent linking group.

As the divalent linking group for W²⁰¹, a divalent hydrocarbon groupwhich may have a substituent is preferable, and as examples thereof, thesame hydrocarbon groups (which may have a substituent) as thosedescribed above for Ya²¹ in the general formula (a2-1) can be mentioned.The divalent linking group for W²⁰¹ may be linear, branched or cyclic,and cyclic is more preferable. Among these, an arylene group having twocarbonyl groups, each bonded to the terminal thereof is preferable.Examples of the arylene group include a phenylene group and anaphthylene group, and a phenylene group is particularly desirable.

As the trivalent linking group for W²⁰¹, a group in which one hydrogenatom has been removed from the aforementioned divalent linking group forW²⁰¹ and a group in which the divalent linking group has been bonded toanother divalent linking group can be mentioned. The trivalent linkinggroup for W²⁰¹ is preferably a group in which 2 carbonyl groups arebonded to an arylene group.

Specific examples of preferable cations represented by formula (ca-1)include cations represented by chemical formulae (ca-1-1) to (ca-1-70)shown below.

In the formulae, g1, g2 and g3 represent recurring numbers, wherein g1is an integer of 1 to 5, g2 is an integer of 0 to 20, and g3 is aninteger of 0 to 20.

In the formulae, R″²⁰¹ represents a hydrogen atom or a substituent, andas the substituent, the same groups as those described above forsubstituting R²⁰¹ to R²⁰⁷ and R²¹⁰ to R²¹² can be mentioned.

Specific examples of preferable cations represented by the formula(ca-2) include a dihphenyliodonium cation and abis(4-tert-butylphenyl)iodonium cation.

Specific examples of preferable cations represented by formula (ca-3)include cations represented by formulae (ca-3-1) to (ca-3-6) shownbelow.

Specific examples of preferable cations represented by formula (ca-4)include cations represented by formulae (ca-4-1) and (ca-4-2) shownbelow.

Specific examples of preferable cations represented by formula (ca-5)include cations represented by formulae (ca-5-1) to (ca-5-3) shownbelow.

Among these examples, as the cation moiety ((M′^(m+))_(1/m)), a cationrepresented by general formula (ca-1) is preferable.

In the resist composition of the present embodiment, as the component(B), one kind of compound may be used, or two or more kinds of compoundsmay be used in combination.

When the resist composition contains the component (B), the amount ofthe component (B) relative to 100 parts by weight of the component (A)is preferably less than 50 parts by weight, more preferably 1 to 40parts by weight, and still more preferably 5 to 25 parts by weight.

When the amount of the component (B) is within the above-mentionedpreferable range, a pattern may be satisfactorily formed. Further, byvirtue of the above-mentioned range, when each of the components aredissolved in an organic solvent, a homogeneous solution may be morereliably obtained and the storage stability of the resist compositionbecomes satisfactory.

<<Basic Component (D)>>

The resist composition of the present embodiment may contain, inaddition to the aforementioned components (A), a basic component(component (D)) which is capable of trapping acid generated uponexposure (i.e., capable of controlling diffusion of acid). The component(D) functions as an acid diffusion control agent, i.e., a quencher whichtraps the acid generated in the resist composition upon exposure.

Examples of the component (D) include a photodecomposable base (D1)(hereafter, referred to as “component (D1)”) which is decomposed uponexposure and then loses the ability of controlling of acid diffusion,and a nitrogen-containing organic compound (D2) (hereafter, referred toas “component (D2)”) which does not fall under the definition ofcomponent (D1). Among these examples, in terms of enhancing sensitivity,reducing roughness and suppressing generation of defects, aphotodecomposable base (component (D1)) is preferable.

—Component (D1)

When a resist pattern is formed using a resist composition containingthe component (D1), the contrast between exposed portions and unexposedportions of the resist film is further improved.

The component (D1) is not particularly limited, as long as it isdecomposed upon exposure and then loses the ability of controlling ofacid diffusion. As the component (D1), at least one compound selectedfrom the group consisting of a compound represented by general formula(d1-1) shown below (hereafter, referred to as “component (d1-1)”), acompound represented by general formula (d1-2) shown below (hereafter,referred to as “component (d1-2)”) and a compound represented by generalformula (d1-3) shown below (hereafter, referred to as “component(d1-3)”) is preferably used.

At exposed portions of the resist film, the components (d1-1) to (d1-3)are decomposed and then lose the ability of controlling of aciddiffusion (i.e., basicity), and therefore the components (d1-1) to(d1-3) cannot function as a quencher, whereas at unexposed portions ofthe resist film, the components (d1-1) to (d1-3) functions as aquencher.

In the formulae, Rd¹ to Rd⁴ represent a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, provided that,the carbon atom adjacent to the sulfur atom within the Rd² in theformula (d1-2) has no fluorine atom bonded thereto; Yd¹ represents asingle bond or a divalent linking group; m represents an integer of 1 ormore; and each M^(m+) independently represents an organic cation havinga valency of m.

{Component (d1-1)}

—Anion Moiety

In formula (d1-1), Rd¹ represents a cyclic group which may have asubstituent, a chain alkyl group which may have a substituent or a chainalkenyl group which may have a substituent, and is the same groups asthose defined above for R′^(201.)

Among these, as the group for Rd¹, an aromatic hydrocarbon group whichmay have a substituent, an aliphatic cyclic group which may have asubstituent and a chain-like alkyl group which may have a substituentare preferable. Examples of the substituent for these groups include ahydroxy group, an oxo group, an alkyl group, an aryl group, a fluorineatom, a fluorinated alkyl group, a lactone-containing cyclic grouprepresented by any one of the aforementioned formulae (a2-r-1) to(a2-r-7), an ether bond, an ester bond, and a combination thereof. Inthe case where an ether bond or an ester bond is included as thesubstituent, the substituent may be bonded via an alkylene group, and alinking group represented by any one of the aforementioned formulae(y-a1-1) to (y-a1-5) is preferable as the substituent.

Preferable examples of the aromatic hydrocarbon group include a phenylgroup, a naphthyl group, and a polycyclic structure containing abicyclooctane skeleton (a polycyclic structure constituted of abicyclooctane skeleton and a ring structure other than bicyclooctane).

Examples of the aliphatic cyclic group include groups in which one ormore hydrogen atoms have been removed from a polycycloalkane such asadamantane, norbornane, isobornane, tricyclodecane ortetracyclododecane.

The chain-like alkyl group preferably has 1 to 10 carbon atoms, andspecific examples thereof include a linear alkyl group such as a methylgroup, an ethyl group, a propyl group, a butyl group, a pentyl group, ahexyl group, a heptyl group, an octyl group, a nonyl or a decyl group,and a branched alkyl group such as a 1-methylethyl group, a1-methylpropyl group, a 2-methylpropyl group, a 1-methylbutyl group, a2-methylbutyl group, a 3-methylbutyl group, a 1-ethylbutyl group, a2-ethylbutyl group, a 1-methylpentyl group, a 2-methylpentyl group, a3-methylpentyl group or a 4-methylpentyl group.

In the case where the chain-like alkyl group is a fluorinated alkylgroup having a fluorine atom or a fluorinated alkyl group, thefluorinated alkyl group preferably has 1 to 11 carbon atoms, morepreferably 1 to 8 carbon atoms, and still more preferably 1 to 4 carbonatoms. The fluorinated alkyl group may contain an atom other thanfluorine. Examples of the atom other than fluorine include an oxygenatom, a sulfur atom and a nitrogen atom.

As Rd¹, a fluorinated alkyl group in which part or all of the hydrogenatoms constituting a linear alkyl group have been substituted withfluorine atom(s) is preferable, and a fluorinated alkyl group in whichall of the hydrogen atoms constituting a linear alkyl group have beensubstituted with fluorine atoms (i.e., a linear perfluoroalkyl group) isparticularly desirable.

Specific examples of preferable anion moieties for the component (d1-1)are shown below.

—Cation Moiety

In formula (d1-1), M^(m+) represents an organic cation having a valencyof m.

As the organic cation for M^(m+), for example, the same cation moietiesas those represented by the aforementioned formulae (ca-1) to (ca-5) arepreferable, cation moieties represented by the aforementioned generalformulae (ca-1) is preferable, and cation moieties represented by theaforementioned formulae (ca-1-1) to (ca-1-70) are still more preferable.

As the component (d1-1), one kind of compound may be used, or two ormore kinds of compounds may be used in combination.

{Component (d1-2)}

—Anion moiety

In formula (d1-2), Rd² represents a cyclic group which may have asubstituent, a chain alkyl group which may have a substituent or a chainalkenyl group which may have a substituent, and is the same groups asthose defined above for R′²⁰¹.

However, the carbon atom adjacent to the sulfur atom within the Rd² hasno fluorine atom bonded thereto. As a result, the anion of the component(d1-2) becomes an appropriately weak acid anion, thereby improving thequenching ability of the component (D).

As Rd², a chain-like alkyl group which may have a substituent or analiphatic cyclic group which may have a substituent is preferable. Thechain-like alkyl group preferably has 1 to 10 carbon atoms, and morepreferably 3 to 10 carbon atoms. As the aliphatic cyclic group, a groupin which one or more hydrogen atoms have been removed from adamantane,norbornane, isobornane, tricyclodecane, tetracyclododecane or camphor(which may have a substituent) is more preferable.

The hydrocarbon group for Rd² may have a substituent. As thesubstituent, the same groups as those described above for substitutingthe hydrocarbon group (e.g., aromatic hydrocarbon group, aliphaticcyclic group, chain-like alkyl group) for Rd¹ in the formula (d1-1) canbe mentioned.

Specific examples of preferable anion moieties for the component (d1-2)are shown below.

—Cation Moiety

In formula (d1-2), M^(m+) is an organic cation having a valency of m,and is the same as defined for M^(m+) in the aforementioned formula(d1-1).

As the component (d1-2), one type of compound may be used, or two ormore types of compounds may be used in combination.

{Component (d1-3)}

—Anion Moiety

In formula (d1-3), Rd³ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, and is the samegroups as those defined above for R′²⁰¹, and a cyclic group containing afluorine atom, a chain alkyl group or a chain alkenyl group ispreferable. Among these, a fluorinated alkyl group is preferable, andmore preferably the same fluorinated alkyl groups as those describedabove for Rd¹.

In formula (d1-3), Rd⁴ represents a cyclic group which may have asubstituent, a chain alkyl group which may have a substituent or a chainalkenyl group which may have a substituent, and is the same groups asthose defined above for R′²⁰¹.

Among these, an alkyl group which may have substituent, an alkoxy groupwhich may have substituent, an alkenyl group which may have substituentor a cyclic group which may have substituent is preferable.

The alkyl group for Rd⁴ is preferably a linear or branched alkyl groupof 1 to 5 carbon atoms, and specific examples include a methyl group, anethyl group, a propyl group, an isopropyl group, an n-butyl group, anisobutyl group, a tert-butyl group, a pentyl group, an isopentyl group,and a neopentyl group. Part of the hydrogen atoms within the alkyl groupfor Rd⁴ may be substituted with a hydroxy group, a cyano group or thelike.

The alkoxy group for Rd⁴ is preferably an alkoxy group of 1 to 5 carbonatoms, and specific examples thereof include a methoxy group, an ethoxygroup, an n-propoxy group, an iso-propoxy group, an n-butoxy group and atert-butoxy group. Among these, a methoxy group and an ethoxy group arepreferable.

The alkenyl group for Rd⁴ is the same as defined for the alkenyl groupfor R′²⁰¹, and a vinyl group, a propenyl group (an allyl group), a1-methylpropenyl group or a 2-methylpropenyl group is preferable. Thesegroups may have an alkyl group of 1 to 5 carbon atoms or a halogenatedalkyl group of 1 to 5 carbon atoms as a substituent.

As the cyclic group for Rd⁴, the same groups as those described abovefor R′²⁰¹ may be mentioned. Among these, as the cyclic group, analicyclic group (e.g., a group in which one or more hydrogen atoms havebeen removed from a cycloalkane such as cyclopentane, cyclohexane,adamantane, norbornane, isobornane, tricyclodecane ortetracyclododecane) or an aromatic group (e.g., a phenyl group or anaphthyl group) is preferable. When Rd⁴ is an alicyclic group, theresist composition can be satisfactorily dissolved in an organicsolvent, thereby improving the lithographic properties. Alternatively,when Rd⁴ is an aromatic group, the resist composition exhibits anexcellent photoabsorption efficiency in a lithography process using EUVor the like as the exposure source, thereby resulting in the improvementof the sensitivity and the lithographic properties.

In formula (d1-3), Yd¹ represents a single bond or a divalent linkinggroup.

The divalent linking group for Yd¹ is not particularly limited, andexamples thereof include a divalent hydrocarbon group (aliphatichydrocarbon group, or aromatic hydrocarbon group) which may have asubstituent and a divalent linking group containing a hetero atom. Thedivalent linking groups are the same as defined for the divalenthydrocarbon group which may have a substituent and the divalent linkinggroup containing a hetero atom explained above as the divalent linkinggroup for Ya²¹ in the aforementioned formula (a2-1).

As Yd¹, a carbonyl group, an ester bond, an amide bond, an alkylenegroup or a combination of these is preferable. As the alkylene group, alinear or branched alkylene group is more preferable, and a methylenegroup or an ethylene group is still more preferable.

Specific examples of preferable anion moieties for the component (d1-3)are shown below.

—Cation Moiety

In formula (d1-3), M^(m+) is an organic cation having a valency of m,and is the same as defined for M^(m+) in the aforementioned formula(d1-1).

As the component (d1-3), one type of compound may be used, or two ormore types of compounds may be used in combination.

As the component (D1), one type of the aforementioned components (d1-1)to (d1-3), or at least two types of the aforementioned components (d1-1)to (d1-3) can be used in combination.

In the case where the resist composition contains the component (D1),the amount of the component (D1) relative to 100 parts by weight of thecomponent (A) is preferably within a range from 0.5 to 20 parts byweight, more preferably from 1 to 15 parts by weight, and still morepreferably from 5 to 10 parts by weight.

When the amount of the component (D1) is at least as large as the lowerlimit of the above-mentioned range, excellent lithographic propertiesand excellent resist pattern shape may be more reliably obtained. On theother hand, when the amount of the component (D1) is no more than theupper limit of the above-mentioned range, sensitivity can be maintainedat a satisfactory level, and through-put becomes excellent.

Production Method of Component (D1):

The production methods of the components (d1-1) and (d1-2) are notparticularly limited, and the components (d1-1) and (d1-2) can beproduced by conventional methods.

Further, the production method of the component (d1-3) is notparticularly limited, and the component (d1-3) can be produced in thesame manner as disclosed in US2012-0149916.

—Component (D2)

The component (D) may contain a nitrogen-containing organic compound(D2) (hereafter, referred to as component (D2)) which does not fallunder the definition of component (D1).

The component (D2) is not particularly limited, as long as it functionsas an acid diffusion control agent, and does not fall under thedefinition of the component (D1). As the component (D2), any of theconventionally known compounds may be selected for use. Among these, analiphatic amine is preferable, and a secondary aliphatic amine ortertiary aliphatic amine is more preferable.

An aliphatic amine is an amine having one or more aliphatic groups, andthe aliphatic groups preferably have 1 to 12 carbon atoms.

Examples of these aliphatic amines include amines in which at least onehydrogen atom of ammonia (NH₃) has been substituted with an alkyl groupor hydroxyalkyl group of no more than 12 carbon atoms (i.e., alkylaminesor alkylalcoholamines), and cyclic amines.

Specific examples of alkylamines and alkylalcoholamines includemonoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine,n-nonylamine, and n-decylamine; dialkylamines such as diethylamine,di-n-propylamine, di-n-heptylamine, di-n-octylamine, anddicyclohexylamine; trialkylamines such as trimethylamine, triethylamine,tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine,tri-n-pentylamine, tri-n-heptylamine, tri-n-octylamine,tri-n-nonylamine, tri-n-decylamine, and tri-n-dodecylamine; and alkylalcohol amines such as diethanolamine, triethanolamine,diisopropanolamine, triisopropanolamine, di-n-octanolamine, andtri-n-octanolamine. Among these, trialkylamines of 5 to 10 carbon atomsare preferable, and tri-n-pentylamine and tri-n-octylamine areparticularly desirable.

Examples of the cyclic amine include heterocyclic compounds containing anitrogen atom as a hetero atom. The heterocyclic compound may be amonocyclic compound (aliphatic monocyclic amine), or a polycycliccompound (aliphatic polycyclic amine).

Specific examples of the aliphatic monocyclic amine include piperidine,and piperazine. The aliphatic polycyclic amine preferably has 6 to 10carbon atoms, and specific examples thereof include 1,5-diazabicyclo[4.3.0]-5-nonene, 1,8-diazabicyclo[5.4.0]-7-undecene,hexamethylenetetramine, and 1,4-diazabicyclo[2.2.2]octane.

Examples of other aliphatic amines includetris(2-methoxymethoxyethyl)amine, tris{2-(2-methoxyethoxy)ethyl}amine,tris{2-(2-methoxyethoxymethoxy)ethyl}amine,tris{2-(1-methoxyethoxy)ethyl}amine, tris{2-(1-ethoxyethoxy)ethyl}amine,tris{2-(1-ethoxypropoxy)ethyl}amine,tris[2-{2-(2-hydroxyethoxy)ethoxy}ethyl]amine and triethanolaminetriacetate, and triethanolamine triacetate is preferable.

Further, as the component (D2), an aromatic amine may be used.

Examples of aromatic amines include 4-dimethylaminopyridine, pyrrole,indole, pyrazole, imidazole and derivatives thereof, as well astribenzylamine, 2,6-diisopropylaniline andN-tert-butoxycarbonylpyrrolidine.

As the component (D2), one kind of compound may be used, or two or morekinds of compounds may be used in combination. When the resistcomposition contains the component (D2), the amount of the component(D2) is typically used in an amount within a range from 0.01 to 5 partsby weight, relative to 100 parts by weight of the component (A). Whenthe amount of the component (D) is within the above-mentioned range, theshape of the resist pattern and the post exposure stability of thelatent image formed by the pattern-wise exposure of the resist layer areimproved.

<<At Least One Compound (E) Selected from the Group Consisting of anOrganic Carboxylic Acid, or a Phosphorus Oxo Acid or DerivativeThereof>>

In the resist composition of the present embodiment, for preventing anydeterioration in sensitivity, and improving the resist pattern shape andthe post exposure stability of the latent image formed by thepattern-wise exposure of the resist layer, at least one compound (E)(hereafter referred to as the component (E)) selected from the groupconsisting of an organic carboxylic acid, or a phosphorus oxo acid orderivative thereof may be added.

Examples of suitable organic carboxylic acids include acetic acid,malonic acid, citric acid, malic acid, succinic acid, benzoic acid, andsalicylic acid.

Examples of phosphorus oxo acids include phosphoric acid, phosphonicacid and phosphinic acid. Among these, phosphonic acid is particularlydesirable.

Examples of oxo acid derivatives include esters in which a hydrogen atomwithin the above-mentioned oxo acids is substituted with a hydrocarbongroup. Examples of the hydrocarbon group include an alkyl group of 1 to5 carbon atoms and an aryl group of 6 to 15 carbon atoms.

Examples of phosphoric acid derivatives include phosphoric acid esterssuch as di-n-butyl phosphate and diphenyl phosphate.

Examples of phosphonic acid derivatives include phosphonic acid esterssuch as dimethyl phosphonate, di-n-butyl phosphonate, phenylphosphonicacid, diphenyl phosphonate and dibenzyl phosphonate.

Examples of phosphinic acid derivatives include phosphinic acid estersand phenylphosphinic acid.

In the resist composition of the present embodiment, as the component(E), one kind of compound may be used, or two or more kinds of compoundsmay be used in combination.

When the resist composition contains the component (E), the amount ofthe component (E) is typically used in an amount within a range from0.01 to 5 parts by weight, relative to 100 parts by weight of thecomponent (A).

<<Fluorine Additive (F)>>

In the present embodiment, the resist composition may further include afluorine additive (hereafter, referred to as “component (F)”) forimparting water repellency to the resist film, or improving lithographyproperties.

As the component (F), for example, a fluorine-containing polymericcompound described in Japanese Unexamined Patent Application, FirstPublication No. 2010-002870, Japanese Unexamined Patent Application,First Publication No. 2010-032994, Japanese Unexamined PatentApplication, First Publication No. 2010-277043, Japanese UnexaminedPatent Application, First Publication No. 2011-13569, and JapaneseUnexamined Patent Application, First Publication No. 2011-128226 can beused.

Specific examples of the component (F) include polymers having astructural unit (f1) represented by general formula (f1-1) shown below.As the polymer, a polymer (homopolymer) consisting of a structural unit(f1) represented by formula (f1-1) shown below; a copolymer of thestructural unit (f1) and the aforementioned structural unit (a1); and acopolymer of the structural unit (f1), a structural unit derived fromacrylic acid or methacrylic acid and the aforementioned structural unit(a1) are preferable. As the structural unit (a1) to be copolymerizedwith the structural unit (f1), a structural unit derived from1-ethyl-1-cyclooctyl (meth)acrylate or a structural unit derived from1-methyl-1-adamantyl (meth)acrylate is preferable.

In the formula, R is the same as defined above; Rf¹⁰² and Rf¹⁰³ eachindependently represents a hydrogen atom, a halogen atom, an alkyl groupof 1 to 5 carbon atoms, or a halogenated alkyl group of 1 to 5 carbonatoms, provided that Rf¹⁰² and Rf¹⁰³ may be the same or different; nf¹represents an integer of 0 to 5; and Rf¹⁰¹ represents an organic groupcontaining a fluorine atom.

In formula (f1-1), R bonded to the carbon atom on the α-position is thesame as defined above. As R, a hydrogen atom or a methyl group ispreferable.

In formula (f1-1), as the halogen atom for Rf¹⁰² and Rf¹⁰³, a fluorineatom is preferable. Examples of the alkyl group of 1 to 5 carbon atomsfor Rf¹⁰² and Rf¹⁰³ include the same alkyl group of 1 to 5 carbon atomsas those described above for R, and a methyl group or an ethyl group ispreferable. Specific examples of the halogenated alkyl group of 1 to 5carbon atoms represented by Rf¹⁰² or Rf¹⁰³ include groups in which partor all of the hydrogen atoms of the aforementioned alkyl groups of 1 to5 carbon atoms have been substituted with halogen atoms. As the halogenatom, a fluorine atom is preferable. Among these, as Rf¹⁰² and Rf¹⁰³, ahydrogen atom, a fluorine atom or an alkyl group of 1 to 5 carbon atomsis preferable, and a hydrogen atom, a fluorine atom, a methyl group oran ethyl group is more preferable.

In formula (f1-1), nf¹ represents an integer of 0 to 5, preferably aninteger of 0 to 3, and more preferably 1 or 2.

In formula (f1-1), Rf¹⁰¹ represents an organic group containing afluorine atom, and is preferably a hydrocarbon group containing afluorine atom.

The hydrocarbon group containing a fluorine atom may be linear, branchedor cyclic, and preferably has 1 to 20 carbon atoms, more preferably 1 to15 carbon atoms, and most preferably 1 to 10 carbon atoms.

It is preferable that the hydrocarbon group having a fluorine atom has25% or more of the hydrogen atoms within the hydrocarbon groupfluorinated, more preferably 50% or more, and most preferably 60% ormore, as the hydrophobicity of the resist film during immersion exposureis enhanced.

Among these, as Rf¹⁰¹, a fluorinated hydrocarbon group of 1 to 6 carbonatoms is preferable, and a trifluoromethyl group, —CH₂—CF₃,—CH₂—CF₂—CF₃, —CH(CF₃)₂, —CH₂—CH₂—CF₃, and —CH₂—CH₂—CF₂—CF₂—CF₂—CF₃ aremost preferable.

The weight average molecular weight (Mw) (the polystyrene equivalentvalue determined by gel permeation chromatography) of the component (F)is preferably 1,000 to 50,000, more preferably 5,000 to 40,000, and mostpreferably 10,000 to 30,000. When the weight average molecular weight(Mw) is no more than the upper limit of the above-mentioned range, theresist may exhibit satisfactory solubility in a resist solvent. On theother hand, when the weight average molecular weight (Mw) is at least aslarge as the lower limit of the above-mentioned range, the waterrepellency of the resist film may become satisfactory.

Further, the dispersity (Mw/Mn) of the component (F) is preferably 1.0to 5.0, more preferably 1.0 to 3.0, and most preferably 1.0 to 2.5.

In the resist composition of the present embodiment, as the component(F), one kind of compound may be used, or two or more kinds of compoundsmay be used in combination.

When the resist composition contains the component (F), the component(F) is used in an amount within a range from 0.5 to 10 parts by weight,relative to 100 parts by weight of the component (A).

<<Organic Solvent (S)>>

The resist composition of the present embodiment may be prepared bydissolving the resist materials for the resist composition in an organicsolvent (hereafter, referred to as “component (S)”).

The component (S) may be any organic solvent which can dissolve therespective components to give a homogeneous solution, and any organicsolvent can be appropriately selected from those which have beenconventionally known as solvents for a chemically amplified resistcomposition.

Examples thereof include lactones such as γ-butyrolactone; ketones suchas acetone, methyl ethyl ketone, cyclohexanone, methyl-n-pentyl ketone,methyl isopentyl ketone, and 2-heptanone; polyhydric alcohols, such asethylene glycol, diethylene glycol, propylene glycol and dipropyleneglycol; compounds having an ester bond, such as ethylene glycolmonoacetate, diethylene glycol monoacetate, propylene glycolmonoacetate, and dipropylene glycol monoacetate; polyhydric alcoholderivatives including compounds having an ether bond, such as amonoalkylether (e.g., monomethylether, monoethylether, monopropyletheror monobutylether) or monophenylether of any of these polyhydricalcohols or compounds having an ester bond (among these, propyleneglycol monomethyl ether acetate (PGMEA) and propylene glycol monomethylether (PGME) are preferable); cyclic ethers such as dioxane; esters suchas methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate,butyl acetate, methyl pyruvate, ethyl pyruvate, methylmethoxypropionate, and ethyl ethoxypropionate; aromatic organic solventssuch as anisole, ethylbenzylether, cresylmethylether, diphenylether,dibenzylether, phenetole, butylphenylether, ethylbenzene,diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymeneand mesitylene; and dimethylsulfoxide (DMSO).

In the resist composition of the present embodiment, as the component(S), one kind of solvent may be used, or two or more kinds of compoundsmay be used as a mixed solvent. Among these examples, PGMEA, PGME,γ-butyrolactone, EL and cyclohexanone are preferable.

Further, as the component (S), a mixed solvent obtained by mixing PGMEAwith a polar solvent is preferable. The mixing ratio (weight ratio) ofthe mixed solvent can be appropriately determined, taking intoconsideration the compatibility of the PGMEA with the polar solvent, butis preferably in the range of 1:9 to 9:1, more preferably from 2:8 to8:2.

Specifically, when EL or cyclohexanone is mixed as the polar solvent,the PGMEA:EL or cyclohexanone weight ratio is preferably from 1:9 to9:1, and more preferably from 2:8 to 8:2. Alternatively, when PGME ismixed as the polar solvent, the PGMEA:PGME weight ratio is preferablyfrom 1:9 to 9:1, more preferably from 2:8 to 8:2, and still morepreferably 3:7 to 7:3. Furthermore, a mixed solvent of PGMEA, PGME andcyclohexanone is also preferable.

Further, as the component (S), a mixed solvent of at least one of PGMEAand EL with γ-butyrolactone is also preferable. The mixing ratio(former:latter) of such a mixed solvent is preferably from 70:30 to95:5.

The amount of the component (S) is not particularly limited, and isappropriately adjusted to a concentration which enables coating of acoating solution to a substrate. In general, the component (S) is usedin an amount such that the solid content of the resist compositionbecomes within the range from 0.1 to 20% by weight, and preferably from0.2 to 15% by weight.

If desired, other miscible additives can also be added to the resistcomposition of the present invention. Examples of such miscibleadditives include additive resins for improving the performance of theresist film, dissolution inhibitors, plasticizers, stabilizers,colorants, halation prevention agents, and dyes.

After dissolving the resist materials in the organic solvent (S), theresist composition of the present embodiment may have impurities or thelike removed by using a polyimide porous film, a polyamide-imide porousfilm, or the like. For example, the resist composition may be subjectedto filtration using a filter formed of a polyimide porous membrane, afilter formed of a polyamide-imide porous film, or a filter formed of apolyimide porous membrane and a polyamide-imide porous film. Examples ofthe polyimide porous membrane and the polyamide-imide porous filminclude those described in Japanese Unexamined Patent Application, FirstPublication No. 2016-155121.

The resist composition according to the present embodiment as describedabove contains a resin component (A1) having a structural unit (a01), astructural unit (a02) and a structural unit (a03).

The structural unit (a01) has an aromatic hydroxy group which functionsas a proton source, and increases the amount of acid generated, so as toimprove the sensitivity. The structural unit (a03) exhibits a highreactivity in the deprotection reaction, so as to improve theresolution. On the other hand, the structural unit (a01) by itself isunsatisfactory in terms of solubility of the exposed portions of theresist film in a developing solution. By using the structural unit (a02)which has an aromatic hydroxy group that functions as a proton sourceand exhibits high solubility in a developing solution in combination,the sensitivity may be improved while suppressing generation of scums orthe like by the improvement of the solubility of the exposed portions ofthe resist film in a developing solution, so as to improve the solution.By the synergistic effects of the structural unit (a01), the structuralunit (a02) and the structural unit (a03), the resist compositionaccording to the present embodiment exhibits improved sensitivity andresolution, and is capable of forming a resist pattern having a highrectangularity with reduced roughness.

(Method of Forming a Resist Pattern)

The method of forming a resist pattern according to the second aspect ofthe present invention includes: using a resist composition according tothe first aspect to form a resist film on a substrate; exposing theresist film; and developing the exposed resist film to form a resistpattern.

The method for forming a resist pattern according to the presentembodiment can be performed, for example, as follows.

Firstly, a resist composition of the first aspect is applied to asubstrate using a spinner or the like, and a bake treatment (postapplied bake (PAB)) is conducted at a temperature of 80 to 150° C. for40 to 120 seconds, preferably 60 to 90 seconds, to form a resist film.

Following selective exposure of the thus formed resist film, either byexposure through a mask having a predetermined pattern formed thereon(mask pattern) using an exposure apparatus such an electron beamlithography apparatus or an EUV exposure apparatus, or by patterning viadirect irradiation with an electron beam without using a mask pattern,baking treatment (post exposure baking (PEB)) is conducted undertemperature conditions of 80 to 150° C. for 40 to 120 seconds, andpreferably 60 to 90 seconds.

Next, the resist film is subjected to a developing treatment. Thedeveloping treatment is conducted using an alkali developing solution inthe case of an alkali developing process, and a developing solutioncontaining an organic solvent (organic developing solution) in the caseof a solvent developing process.

After the developing treatment, it is preferable to conduct a rinsetreatment. The rinse treatment is preferably conducted using pure waterin the case of an alkali developing process, and a rinse solutioncontaining an organic solvent in the case of a solvent developingprocess.

In the case of a solvent developing process, after the developingtreatment or the rinsing, the developing solution or the rinse liquidremaining on the pattern can be removed by a treatment using asupercritical fluid.

After the developing treatment or the rinse treatment, drying isconducted. If desired, bake treatment (post bake) can be conductedfollowing the developing.

In this manner, a resist pattern can be formed.

The substrate is not specifically limited and a conventionally knownsubstrate can be used. For example, substrates for electroniccomponents, and such substrates having wiring patterns formed thereoncan be used. Specific examples of the material of the substrate includemetals such as silicon wafer, copper, chromium, iron and aluminum; andglass. Suitable materials for the wiring pattern include copper,aluminum, nickel, and gold.

Further, as the substrate, any one of the above-mentioned substratesprovided with an inorganic and/or organic film on the surface thereofmay be used. As the inorganic film, an inorganic antireflection film(inorganic BARC) can be used. As the organic film, an organicantireflection film (organic BARC) and an organic film such as alower-layer organic film used in a multilayer resist method can be used.

Here, a “multilayer resist method” is method in which at least one layerof an organic film (lower-layer organic film) and at least one layer ofa resist film (upper resist film) are provided on a substrate, and aresist pattern formed on the upper resist film is used as a mask toconduct patterning of the lower-layer organic film. This method isconsidered as being capable of forming a pattern with a high aspectratio. More specifically, in the multilayer resist method, a desiredthickness can be ensured by the lower-layer organic film, and as aresult, the thickness of the resist film can be reduced, and anextremely fine pattern with a high aspect ratio can be formed.

The multilayer resist method is broadly classified into a method inwhich a double-layer structure consisting of an upper-layer resist filmand a lower-layer organic film is formed (double-layer resist method),and a method in which a multilayer structure having at least threelayers consisting of an upper-layer resist film, a lower-layer organicfilm and at least one intermediate layer (thin metal film or the like)provided between the upper-layer resist film and the lower-layer organicfilm (triple-layer resist method).

The wavelength to be used for exposure is not particularly limited andthe exposure can be conducted using radiation such as ArF excimer laser,KrF excimer laser, F₂ excimer laser, extreme ultraviolet rays (EUV),vacuum ultraviolet rays (VUV), electron beam (EB), X-rays, and softX-rays. The resist composition of the present embodiment is effective toKrF excimer laser, ArF excimer laser, EB and EUV, and more effective toArF excimer laser, EB and EUV, and most effective to EB and EUV. Thatis, the method of forming a resist pattern according to the presentembodiment is effective in the case where the step of exposing theresist film includes exposing the resist film with extreme ultravioletrays (EUV) or electron beam (EB).

The exposure of the resist film can be either a general exposure (dryexposure) conducted in air or an inert gas such as nitrogen, orimmersion exposure (immersion lithography).

In immersion lithography, the region between the resist film and thelens at the lowermost point of the exposure apparatus is pre-filled witha solvent (immersion medium) that has a larger refractive index than therefractive index of air, and the exposure (immersion exposure) isconducted in this state.

The immersion medium preferably exhibits a refractive index larger thanthe refractive index of air but smaller than the refractive index of theresist film to be exposed. The refractive index of the immersion mediumis not particularly limited as long as it satisfies the above-mentionedrequirements.

Examples of this immersion medium which exhibits a refractive index thatis larger than the refractive index of air but smaller than therefractive index of the resist film include water, fluorine-based inertliquids, silicon-based solvents and hydrocarbon-based solvents.

Specific examples of the fluorine-based inert liquids include liquidscontaining a fluorine-based compound such as C₃HC₂F, C₄F₉OCH₃, C₄F₉OC₂H₅or C₅H₃F₇ as the main component, which have a boiling point within arange from 70 to 180° C. and preferably from 80 to 160° C. Afluorine-based inert liquid having a boiling point within theabove-mentioned range is advantageous in that the removal of theimmersion medium after the exposure can be conducted by a simple method.

As a fluorine-based inert liquid, a perfluoroalkyl compound in which allof the hydrogen atoms of the alkyl group are substituted with fluorineatoms is particularly desirable. Examples of these perfluoroalkylcompounds include perfluoroalkylether compounds and perfluoroalkylaminecompounds.

Specifically, one example of a suitable perfluoroalkylether compound isperfluoro(2-butyl-tetrahydrofuran) (boiling point 102° C.), and anexample of a suitable perfluoroalkylamine compound isperfluorotributylamine (boiling point 174° C.).

As the immersion medium, water is preferable in terms of cost, safety,environment and versatility.

As an example of the alkali developing solution used in an alkalideveloping process, a 0.1 to 10% by weight aqueous solution oftetramethylammonium hydroxide (TMAH) can be given.

As the organic solvent contained in the organic developing solution usedin a solvent developing process, any of the conventional organicsolvents can be used which are capable of dissolving the component (A)(prior to exposure). Specific examples of the organic solvent includepolar solvents such as ketone solvents, ester solvents, alcoholsolvents, nitrile solvents, amide solvents and ether solvents, andhydrocarbon solvents.

A ketone solvent is an organic solvent containing C—C(═O)—C within thestructure thereof. An ester solvent is an organic solvent containingC—C(═O)—O—C within the structure thereof. An alcohol solvent is anorganic solvent containing an alcoholic hydroxy group in the structurethereof. An “alcoholic hydroxy group” refers to a hydroxy group bondedto a carbon atom of an aliphatic hydrocarbon group. A nitrile solvent isan organic solvent containing a nitrile group in the structure thereof.An amide solvent is an organic solvent containing an amide group withinthe structure thereof. An ether solvent is an organic solvent containingC—O—C within the structure thereof.

Some organic solvents have a plurality of the functional groups whichcharacterizes the aforementioned solvents within the structure thereof.In such a case, the organic solvent can be classified as any type of thesolvent having the characteristic functional group. For example,diethylene glycol monomethyl ether may be classified as an alcoholsolvent or an ether solvent.

A hydrocarbon solvent consists of a hydrocarbon which may behalogenated, and does not have any substituent other than a halogenatom. As the halogen atom, a fluorine atom is preferable.

As the organic solvent contained in the organic developing solution,among these, a polar solvent is preferable, and ketone solvents, estersolvents and nitrile solvents are preferable.

Examples of ketone solvents include 1-octanone, 2-octanone, 1-nonanone,2-nonanone, acetone, 4-heptanone, 1-hexanone, 2-hexanone, diisobutylketone, cyclohexanone, methylcyclohexanone, phenylacetone, methyl ethylketone, methyl isobutyl ketone, acetylacetone, acetonylacetone, ionone,diacetonylalcohol, acetylcarbinol, acetophenone, methyl naphthyl ketone,isophorone, propylenecarbonate, γ-butyrolactone and methyl amyl ketone(2-heptanone). Among these examples, as a ketone solvent, methyl amylketone (2-heptanone) is preferable.

Examples of ester solvents include methyl acetate, butyl acetate, ethylacetate, isopropyl acetate, amyl acetate, isoamyl acetate, ethylmethoxyacetate, ethyl ethoxyacetate, ethylene glycol monoethyl etheracetate, ethylene glycol monopropyl ether acetate, ethylene glycolmonobutyl ether acetate, ethylene glycol monophenyl ether acetate,diethylene glycol monomethyl ether acetate, diethylene glycol monopropylether acetate, diethylene glycol monoethyl ether acetate, diethyleneglycol monophenyl ether acetate, diethylene glycol monobutyl etheracetate, diethylene glycol monoethyl ether acetate, 2-methoxybutylacetate, 3-methoxybutyl acetate, 4-methoxybutyl acetate,3-methyl-3-methoxybutyl acetate, 3-ethyl-3-methoxybutyl acetate,propylene glycol monomethyl ether acetate, propylene glycol monoethylether acetate, propylene glycol monopropyl ether acetate, 2-ethoxybutylacetate, 4-ethoxybutyl acetate, 4-propoxybutyl acetate, 2-methoxypentylacetate, 3-methoxypentyl acetate, 4-methoxypentyl acetate,2-methyl-3-methoxypentyl acetate, 3-methyl-3-methoxypentyl acetate,3-methyl-4-methoxypentyl acetate, 4-methyl-4-methoxypentyl acetate,propylene glycol diacetate, methyl formate, ethyl formate, butylformate, propyl formate, ethyl lactate, butyl lactate, propyl lactate,ethyl carbonate, propyl carbonate, butyl carbonate, methyl pyruvate,ethyl pyruvate, propyl pyruvate, butyl pyruvate, methyl acetoacetate,ethyl acetoacetate, methyl propionate, ethyl propionate, propylpropionate, isopropyl propionate, methyl 2-hydroxypropionate, ethyl2-hydroxypropionate, methyl-3-methoxypropionate,ethyl-3-methoxypropionate, ethyl-3-ethoxypropionate andpropyl-3-methoxypropionate. Among these examples, as an ester solvent,butyl acetate is preferable. Among these examples, as an ester solvent,butyl acetate is preferable.

Examples of nitrile solvents include acetonitrile, propionitrile,valeronitrile, and butyronitrile.

If desired, the organic developing solution may have a conventionaladditive blended. Examples of the additive include surfactants. Thesurfactant is not particularly limited, and for example, an ionic ornon-ionic fluorine and/or silicon surfactant may be used. As thesurfactant, a non-ionic surfactant is preferable, and a non-ionicfluorine surfactant or a non-ionic silicon surfactant is morepreferable.

When a surfactant is added, the amount thereof based on the total amountof the organic developing solution is generally 0.001 to 5% by weight,preferably 0.005 to 2% by weight, and more preferably 0.01 to 0.5% byweight.

The developing treatment may be performed by a conventional developingmethod. Examples thereof include a method in which the substrate isimmersed in the developing solution for a predetermined time (a dipmethod), a method in which the developing solution is cast up on thesurface of the substrate by surface tension and maintained for apredetermined period (a puddle method), a method in which the developingsolution is sprayed onto the surface of the substrate (spray method),and a method in which the developing solution is continuously ejectedfrom a developing solution ejecting nozzle while scanning at a constantrate to apply the developing solution to the substrate while rotatingthe substrate at a constant rate (dynamic dispense method).

As the organic solvent contained in the rinse liquid used in the rinsetreatment after the developing treatment in the case of a solventdeveloping process, any of the aforementioned organic solvents containedin the organic developing solution can be used which hardly dissolvesthe resist pattern. In general, at least one solvent selected from thegroup consisting of hydrocarbon solvents, ketone solvents, estersolvents, alcohol solvents, amide solvents and ether solvents is used.Among these, at least one solvent selected from the group consisting ofhydrocarbon solvents, ketone solvents, ester solvents, alcohol solventsand amide solvents is preferable, more preferably at least one solventselected from the group consisting of alcohol solvents and estersolvents, and an alcohol solvent is particularly desirable.

The alcohol solvent used for the rinse liquid is preferably a monohydricalcohol of 6 to 8 carbon atoms, and the monohydric alcohol may belinear, branched or cyclic. Specific examples thereof include 1-hexanol,1-heptanol, 1-octanol, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol,3-heptanol, 3-octanol, 4-octanol and benzyl alcohol. Among these,1-hexanol, 2-heptanol and 2-hexanol are preferable, and 1 hexanol and2-hexanol are more preferable.

As the organic solvent, one kind of solvent may be used alone, or two ormore kinds of solvents may be used in combination. Further, an organicsolvent other than the aforementioned examples or water may be mixedtogether. However, in consideration of the development characteristics,the amount of water within the rinse liquid, based on the total amountof the rinse liquid is preferably 30% by weight or less, more preferably10% by weight or less, still more preferably 5% by weight or less, andmost preferably 3% by weight or less.

If desired, the rinse solution may have a conventional additive blended.Examples of the additive include surfactants. Examples of the additiveinclude surfactants. As the surfactant, the same surfactants as thosedescribed above can be mentioned, a non-ionic surfactant is preferable,and a non-ionic fluorine surfactant or a non-ionic silicon surfactant ismore preferable.

When a surfactant is added, the amount thereof based on the total amountof the rinse liquid is generally 0.001 to 5% by weight, preferably 0.005to 2% by weight, and more preferably 0.01 to 0.5% by weight.

The rinse treatment using a rinse liquid (washing treatment) can beconducted by a conventional rinse method. Examples of the rinse methodinclude a method in which the rinse liquid is continuously applied tothe substrate while rotating it at a constant rate (rotational coatingmethod), a method in which the substrate is immersed in the rinse liquidfor a predetermined time (dip method), and a method in which the rinseliquid is sprayed onto the surface of the substrate (spray method).

According to the method of forming a resist composition of the presentembodiment described above, since the resist composition according tothe first aspect described above is used, sensitivity and resolution maybe improved, and a resist pattern having a high rectangularity withreduced roughness may be formed.

EXAMPLES

As follows is a description of examples of the present invention,although the scope of the present invention is by no way limited bythese examples.

<Synthesis of Polymeric Compound (A1)>

10.0 g of monomer (a01-1-1pre), 13.3 g of monomer (a03-1-1) and 2.4 g ofdimethyl-2,2′-azobisisoutyrate (V-601) as a polymerization initiatorwere dissolved in 50.0 g of methyl ethyl ketone (MEK), followed byheating to 85° C. in a nitrogen atmosphere, and stirring for 5 hours.Then, 9.4 g of acetic acid and 160 g of methanol was added to thereaction liquid, and a deprotection reaction was conducted at 30° C. for8 hours. After the reaction finished, the obtained reaction liquid waswashed by precipitating in 2,500 g of heptane. The obtained white solidwas subjected to filtration, followed by drying under reduced pressurefor one night, so as to obtain 12.3 g of a polymeric compound (A-1) asan objective compound.

With respect to the polymeric compound (A-1), the weight averagemolecular weight (Mw) and the polydispersity (Mw/Mn) were determined bythe polystyrene equivalent value as measured by gel permeationchromatography (GPC). As a result, it was found that the weight averagemolecular weight was 7,000, and the polydispersity was 1.70. Thecomposition of the copolymer (ratio (molar ratio) of the respectivestructural units within the structural formula) as determined by ¹³C-NMRwas 1/m=50/50.

Using the compounds shown below, polymeric compounds (A-2) to (A-26)having a compositional ratio shown in Table 1 were synthesized in thesame manner.

With respect to each polymeric compound, the compositional ratio of thepolymers (the molar ratio of the respective structural units in thepolymeric compound) as determined by ¹³C-NMR, the weight averagemolecular weight (Mw) and the polydispersity (Mw/Mn) determined by thepolystyrene equivalent value as measured by GPC are also shown in Table1.

Polymeric compounds (A-1) to (A-26) obtained by the above synthesisexamples are shown below.

The structural unit represented by chemical formula (a01-1-1) shownbelow and the structural unit represented by chemical formula (a02-1-1)shown below which constitute the above copolymers are obtained bycopolymerizing the monomer represented by the aforementioned chemicalformula (a01-1-1pre) and the monomer represented by the aforementionedchemical formula (a02-1-1pre), respectively.

TABLE 1 Weight average molecular Polymeric Copolymer compositional ratioof weight Polydispersity compound polymeric compound (molar ratio) (Mw)(Mw/Mn) Synthesis (A-1) (a01-1-1)/(a03-1-1) = 50/50 7000 1.70 Example 1Synthesis (A-2) (a02-1-1)/(a03-1-1) = 50/50 6800 1.66 Example 2Synthesis (A-3) (a01-1-1)/(a03-1-2) = 50/50 7200 1.72 Example 3Synthesis (A-4) (a02-1-1)/(a03-1-2) = 50/50 7000 1.67 Example 4Synthesis (A-5) (a01-1-1)/(a03-1-3) = 50/50 6800 1.67 Example 5Synthesis (A-6) (a02-1-1)/(a03-1-3) = 50/50 7200 1.66 Example 6Synthesis (A-7) (a01-1-1)/(a03-1-4) = 50/50 7000 1.70 Example 7Synthesis (A-8) (a02-1-1)/(a03-1-4) = 50/50 6800 1.66 Example 8Synthesis (A-9) (a01-1-1)/(a03-1-5) = 50/50 7200 1.71 Example 9Synthesis (A-10) (a02-1-1)/(a03-1-5) = 50/50 6600 1.74 Example 10Synthesis (A-11) (a01-1-1)/(a03-1-6) = 50/50 6700 1.70 Example 11Synthesis (A-12) (a02-1-1)/(a03-1-6) = 50/50 7300 1.69 Example 12Synthesis (A-13) (a01-1-1)/(a03-1-7) = 50/50 7100 1.72 Example 13Synthesis (A-14) (a02-1-1)/(a03-1-7) = 50/50 6500 1.69 Example 14Synthesis (A-15) (a01-1-1)/(a03-1-8) = 50/50 6800 1.74 Example 15Synthesis (A-16) (a02-1-1)/(a03-1-8) = 50/50 7000 1.72 Example 16Synthesis (A-17) (a01-1-1)/(a03-1-9) = 50/50 7300 1.64 Example 17Synthesis (A-18) (a02-1-1)/(a03-1-9) = 50/50 7100 1.67 Example 18Synthesis (A-19) (a01-1-1)/(a1-1) = 50/50 7000 1.68 Example 19 Synthesis(A-20) (a02-1-1)/(a1-1) = 50/50 7200 1.69 Example 20 Synthesis (A-21)(a01-1-1)/(a1-2) = 50/50 7300 1.64 Example 21 Synthesis (A-22)(a02-1-1)/(a1-2) = 50/50 7100 1.67 Example 22 Synthesis (A-23)(a01-1-1)/(a1-3) = 50/50 6700 1.71 Example 23 Synthesis (A-24)(a02-1-1)/(a1-3) = 50/50 6600 1.73 Example 24 Synthesis (A-25)(a01-1-1)/(a1-4) = 50/50 7400 1.72 Example 25 Synthesis (A-26)(a02-1-1)/(a1-4) = 50/50 7300 1.70 Example 26

<Production of Resist Composition>

Examples 1 to 9, Comparative Examples 1 to 8

The components shown in Tables 2 and 3 were mixed together and dissolvedto obtain each resist composition.

TABLE 2 Component Component Component Component (A) (B) (D) (S) Example1 (A)-1 (A)-2 (B)-1 (D)-1 (S)-1 [50] [50] [20] [10] [6000] Example 2(A)-3 (A)-4 (B)-1 (D)-1 (S)-1 [50] [50] [20] [10] [6000] Example 3 (A)-5(A)-6 (B)-1 (D)-1 (S)-1 [50] [50] [20] [10] [6000] Example 4 (A)-7 (A)-8(B)-1 (D)-1 (S)-1 [50] [50] [20] [10] [6000] Example 5 (A)-9 (A)-10(B)-1 (D)-1 (S)-1 [50] [50] [20] [10] [6000] Example 6 (A)-11 (A)-12(B)-1 (D)-1 (S)-1 [50] [50] [20] [10] [6000] Example 7 (A)-13 (A)-14(B)-1 (D)-1 (S)-1 [50] [50] [20] [10] [6000] Example 8 (A)-15 (A)-16(B)-1 (D)-1 (S)-1 [50] [50] [20] [10] [6000] Example 9 (A)-17 (A)-18(B)-1 (D)-1 (S)-1 [50] [50] [20] [10] [6000]

TABLE 3 Component Component Component Component (A) (B) (D) (S)Comparative (A)-1 — (B)-1 (D)-1 (S)-1 Example 1 [100] [20] [10] [6000]Comparative (A)-2 — (B)-1 (D)-1 (S)-1 Example 2 [100] [20] [10] [6000]Comparative (A)-19 — (B)-1 (D)-1 (S)-1 Example 3 [100] [20] [10] [6000]Comparative (A)-20 — (B)-1 (D)-1 (S)-1 Example 4 [100] [20] [10] [6000]Comparative (A)-19 (A)-20 (B)-1 (D)-1 (S)-1 Example 5 [50] [50] [20][10] [6000] Comparative (A)-21 (A)-22 (B)-1 (D)-1 (S)-1 Example 6 [50][50] [20] [10] [6000] Comparative (A)-23 (A)-24 (B)-1 (D)-1 (S)-1Example 7 [50] [50] [20] [10] [6000] Comparative (A)-25 (A)-26 (B)-1(D)-1 (S)-1 Example 8 [50] [50] [20] [10] [6000]

In Tables 2 and 3, the reference characters indicate the following. Thevalues in brackets [ ] indicate the amount (in terms of parts by weight)of the component added.

(A)-1 to (A)-26: the aforementioned polymeric compounds (A-1) to (A-26).

(B)-1: an acid generator represented by chemical formula (B-1) shownbelow.

(D)-1: Acid diffusion control agent represented by chemical formula(D-1) shown below.

(S)-1: a mixed solvent of propylene glycol monomethyl etheracetate/propylene glycol monomethyl ether=60/40 (weight ratio).

<Formation of Resist Pattern>

Each of the resist compositions of examples and comparative examples wasapplied to an 8-inch silicon substrate which had been treated withhexamethyldisilazane (HMDS) using a spinner, and was then prebaked (PAB)on a hot plate at 110° C. for 60 seconds and dried, so as to form aresist film having a film thickness of 30 nm.

A drawing (exposure) was carried out on the resist film using anelectron beam lithography system JEOL-JBX-9300FS (manufactured by JEOLLtd.) with acceleration voltage of 100 kV and a target size of 1:1line-and-space pattern (line width: 50 nm to 16 nm) (hereinafterreferred to as an “LS pattern”). Then, a post exposure bake (PEB)treatment was conducted at 90° C. for 60 seconds.

Thereafter, alkali developing was conducted for 60 seconds at 23° C. ina 2.38% by weight aqueous solution of tetramethylammonium hydroxide(TMAH) (product name: NMD-3; manufactured by Tokyo Ohka Kogyo Co.,Ltd.). Then, water rinsing was conducted for 15 seconds using purewater. As a result, a 1:1 LS pattern having a line width of 50 to 16 nmwas formed.

[Evaluation of Optimum Exposure Dose (Eop)]

The optimum exposure dose Eop (μC/cm²) with which the LS pattern havinga target size (line width: 50 nm) was formed in the above “Formation ofresist pattern” was determined. The results are indicated under “Eop(μC/cm²)” in Tables 4 and 5.

[Evaluation of Line Width Roughness (LWR)]

With respect to the LS pattern formed in the above “formation of resistpattern”, 3σ was determined as a yardstick for indicating LWR. Theresults are indicated under “LWR (nm)” in Tables 4 and 5.

“3σ” indicates a value of 3 times the standard deviation (σ) (i.e., 3σ)(unit: nm) determined by measuring the line positions at 400 points inthe lengthwise direction of the line using a scanning electronmicroscope (product name: S-9380, manufactured by HitachiHigh-Technologies Corporation; acceleration voltage: 800V).

The smaller this 3σ value is, the lower the level of roughness on theside walls of the line, indicating that an LS pattern with a uniformwidth was obtained.

[Evaluation of Resolution]

When the LS pattern was formed by gradually increasing the exposure dosefrom the optimum exposure dose Eop, the minimum dimension of the pattern(line width) that was resolved without collapsing was determined using ascanning electron microscope S-9380 (manufactured by Hitachi HighTechnologies Co., Ltd.). The results are indicated under “Resolution(nm)” in Tables 4 and 5.

[Evaluation of Resist Pattern Shape]

The cross-sectional shape of the LS pattern formed in the above“Formation of resist pattern” was observed using a scanning electronmicroscope (product name: SU8000, manufactured by HitachiHigh-Technologies Corporation; acceleration voltage: 300V). The shapewas evaluated in accordance with the following criteria. The results areindicated under “Pattern shape” in Tables 4 and 5.

A: The cross-sectional shape of the pattern is rectangular, and theperpendicularity is high.

B: The perpendicularity of the cross-sectional shape of the pattern isslightly poor as compared to “A”.

C: The cross-sectional shape of the pattern is top-rounding (the top ofthe pattern is rounded) or has a T-top shape.

TABLE 4 PAB PEB Eop LWR Resolution Patten (° C.) (° C.) [μC/cm²] [nm][nm] shape Example 1 110 90 102 4.5 26 A Example 2 110 90 105 4.4 28 BExample 3 110 90  95 4.2 26 A Example 4 110 90  86 4.6 28 B Example 5110 90  89 4.3 26 A Example 6 110 90  98 4.4 30 B Example 7 110 90  924.5 30 A Example 8 110 90  92 4.8 30 B Example 9 110 90 108 4.7 30 B

TABLE 5 PAB PEB Eop LWR Resolution Patten (° C.) (° C.) [μC/cm²] [nm][nm] shape Comparative 110 90 140 5.1 40 C Example 1 Comparative 110 90 85 6.4 50 C Example 2 Comparative 110 90 159 6.1 50 C Example 3Comparative 110 90 100 7.7 50 C Example 4 Comparative 110 90 132 6.7 50C Example 5 Comparative 110 90 154 6.2 50 C Example 6 Comparative 110 90161 7.1 50 C Example 7 Comparative 110 90 158 7.3 50 C Example 8

As seen from the results shown in Tables 4 and 5, it was confirmed that,in Example 1 in which polymeric compounds (A-1) and (A-2) were used incombination, the sensitivity and the resolution were improved, and aresist pattern having a high rectangularity with reduced roughness couldbe formed, as compared to Comparative Examples 1 and 2 in which only oneof polymeric compounds (A-1) and (A-2) was used, and Comparative Example5 in which polymeric compounds (A-19) and (A-20) were used incombination.

As seen from the results shown in Tables 4 and 5, it was confirmed thatthe resist compositions of Examples 1 to 9 exhibited improvedresolution, as compared to Comparative Examples 1 to 8.

While preferred embodiments of the invention have been described andillustrated above, it should be understood that these are exemplary ofthe invention and are not to be considered as limiting. Additions,omissions, substitutions, and other modifications can be made withoutdeparting from the spirit or scope of the present invention.Accordingly, the invention is not to be considered as being limited bythe foregoing description, and is only limited by the scope of theappended claims.

What is claimed is:
 1. A resist composition which generates acid uponexposure and exhibits changed solubility in a developing solution underaction of acid, the resist composition comprising a resin component (A1)and an acid-generator component (B), the resin component (A) including:a structural unit (a01) derived from a compound represented by generalformula (a01-1) shown below, a structural unit (a02) derived from acompound represented by general formula (a02-1) shown below, and astructural unit (a03) derived from a compound represented by generalformula (a03-1) shown below:

wherein W⁰¹ represents a polymerizable group-containing group; providedthat the polymerizable group-containing group represented by W⁰¹contains no oxygen atom; Wa⁰¹ represents an aromatic hydrocarbon group;part or all of the hydrogen atoms of the aromatic hydrocarbon group maybe substituted with a substituent other that a hydroxy group; Wa⁰¹ andW⁰¹ may form a condensed ring; n01 represents 1 or 2; W⁰² represents apolymerizable group-containing group; provided that the polymerizablegroup-containing group represented by W⁰² contains an oxygen atom; Wa⁰²represents an aromatic hydrocarbon group; part or all of the hydrogenatoms of the aromatic hydrocarbon group may be substituted with asubstituent selected from the group consisting of a carboxy group, ahalogen atom, an alkoxy group, and an alkyloxycarbonyl group; Wa⁰² andW⁰² may form a condensed ring; n02 represents 1 or 2; W⁰³ represents apolymerizable group-containing group; provided that the polymerizablegroup-containing group represented by W⁰³ may contain an oxygen atom;Ya⁰³ represents a carbon atom; Xa⁰³ represents a group which forms analicyclic hydrocarbon group together with Ya⁰³; Re⁰⁰ represents ahydrocarbon group which may have a substituent; and the acid-generatorcomponent (B) is a compound represented by general formula (b-1): shownbelow:

wherein R¹⁰¹ represents a cyclic group which may have a substituent;R¹⁰² represents a fluorine atom or a fluorinated alkyl group having 1 to5 carbon atoms; Y¹⁰¹ represents a divalent group containing an oxygenatom; V¹⁰¹ represents a single bond, an alkylene group or a fluorinatedalkylene group; m represents an integer of 1 or more; and M′^(m+)represents an m-valent onium cation.
 2. The resist composition accordingto claim 1, wherein the structural unit (a01) is a structural unitrepresented by general formula (a01-11) shown below:

wherein R⁰¹ represents a hydrogen atom, an alkyl group of 1 to 5 carbonatoms or a halogenated alkyl group of 1 to 5 carbon atoms; Wa⁰¹represents an aromatic hydrocarbon group; part or all of the hydrogenatoms of the aromatic hydrocarbon group may be substituted with asubstituent other that a hydroxy group; and n01 represents 1 or
 2. 3.The resist composition according to claim 1, wherein the structural unit(a02) is a structural unit represented by general formula (a02-11) shownbelow:

wherein R⁰² represents a hydrogen atom, an alkyl group of 1 to 5 carbonatoms or a halogenated alkyl group of 1 to 5 carbon atoms; Wa⁰²represents an aromatic hydrocarbon group; part or all of the hydrogenatoms of the aromatic hydrocarbon group may be substituted with asubstituent selected from the group consisting of a carboxy group, ahalogen atom, an alkoxy group, and an alkyloxycarbonyl group; and n02represents 1 or
 2. 4. The resist composition according to claim 2,wherein the structural unit (a02) is a structural unit represented bygeneral formula (a02-11) shown below:

wherein R⁰² represents a hydrogen atom, an alkyl group of 1 to 5 carbonatoms or a halogenated alkyl group of 1 to 5 carbon atoms; Wa⁰²represents an aromatic hydrocarbon group; part or all of the hydrogenatoms of the aromatic hydrocarbon group may be substituted with asubstituent other that a hydroxy group; and n02 represents 1 or
 2. 5.The resist composition according to claim 4, wherein the resin component(A1) is a mixed resin of a polymeric compound (A11) having a repeatingstructure of the structural unit (a01) and the structural unit (a02) anda polymeric compound (A12) having a repeating structure of thestructural unit (a01) and the structural unit (a03).
 6. A method offorming a resist pattern, comprising: to forming a resist film using theresist composition according to claim 1; exposing the resist film; anddeveloping the exposed resist film to form a resist pattern.
 7. Themethod according to claim 6, wherein the resist film is exposed toextreme ultraviolet (EUV) or electron beam (EB).
 8. A resist compositionwhich generates acid upon exposure and exhibits changed solubility in adeveloping solution under action of acid, the resist compositioncomprising a resin component (A1) including: a structural unit (a01)derived from a compound represented by general formula (a01-1) shownbelow, a structural unit (a02) derived from a compound represented bygeneral formula (a02-1) shown below, and a structural unit (a03) is astructural unit represented by general formula (a03-11) or (a03-12)shown below:

wherein W⁰¹ represents a polymerizable group-containing group; providedthat the polymerizable group-containing group represented by W⁰¹contains no oxygen atom; Wa⁰¹ represents an aromatic hydrocarbon group;part or all of the hydrogen atoms of the aromatic hydrocarbon group maybe substituted with a substituent other that a hydroxy group; Wa⁰¹ andW⁰¹ may form a condensed ring; n01 represents 1 or 2; wherein W⁰²represents a polymerizable group-containing group; provided that thepolymerizable group-containing group represented by W⁰² contains anoxygen atom; Wa⁰² represents an aromatic hydrocarbon group; part or allof the hydrogen atoms of the aromatic hydrocarbon group may besubstituted with a substituent other that a hydroxy group; Wa⁰² and W⁰²may form a condensed ring; n02 represents 1 or 2; W⁰³ represents apolymerizable group-containing group; provided that the polymerizablegroup-containing group represented by W⁰³ may contain an oxygen atom;Ya⁰³ represents a carbon atom; Xa⁰³ represents a group which forms amonocyclic ring together with Ya⁰³; Ra⁰⁰ represents a hydrocarbon groupwhich may have a substituent; and wherein R⁰³ represents a hydrogenatom, an alkyl group of 1 to 5 carbon atoms or a halogenated alkyl groupof 1 to 5 carbon atoms; Ya⁰³ represents a carbon atom; Xa⁰³ represents agroup which forms a monocyclic alicyclic hydrocarbon group together withYa⁰³; Ra⁰⁰¹ to Ra⁰⁰³ each independently represents a hydrogen atom, amonovalent saturated chain hydrocarbon group of 1 to 10 carbon atoms ora monovalent saturated aliphatic cyclic hydrocarbon group of 3 to 20carbon atoms, provided that part or all of the hydrogen atoms of thesaturated chain hydrocarbon or the saturated aliphatic cyclichydrocarbon may be substituted; two or more of Ra⁰⁰¹ to Ra⁰⁰³ may bemutually bonded to form a ring structure;

wherein R⁰³ represents a hydrogen atom, an alkyl group of 1 to 5 carbonatoms or a halogenated alkyl group of 1 to 5 carbon atoms; Ya⁰³represents a carbon atom; Xa⁰³ represents a group which forms analicyclic hydrocarbon group together with Ya⁰³; and Ra⁰⁰⁴ represents anaromatic hydrocarbon group which may have a substituent.
 9. The resistcomposition according to claim 8, wherein the structural unit (a01) is astructural unit represented by the general formula (a01-11) shown below:

wherein R⁰¹ represents a hydrogen atom, an alkyl group of 1 to 5 carbonatoms or a halogenated alkyl group of 1 to 5 carbon atoms; Wa⁰¹represents an aromatic hydrocarbon group; part or all of the hydrogenatoms of the aromatic hydrocarbon group may be substituted with asubstituent other that a hydroxy group; and n01 represents 1 or
 2. 10.The resist composition according to claim 8, wherein the structural unit(a02) is a structural unit represented by the general formula (a02-11)shown below:

wherein R⁰² represents a hydrogen atom, an alkyl group of 1 to 5 carbonatoms or a halogenated alkyl group of 1 to 5 carbon atoms; Wa⁰²represents an aromatic hydrocarbon group; part or all of the hydrogenatoms of the aromatic hydrocarbon group may be substituted with asubstituent other that a hydroxy group; and n02 represents 1 or
 2. 11.The resist composition according to claim 8, wherein the structural unit(a01) is a structural unit represented by the general formula (a01-11)shown below:

wherein R⁰¹ represents a hydrogen atom, an alkyl group of 1 to 5 carbonatoms or a halogenated alkyl group of 1 to 5 carbon atoms; Wa⁰¹represents an aromatic hydrocarbon group; part or all of the hydrogenatoms of the aromatic hydrocarbon group may be substituted with asubstituent other that a hydroxy group; and n01 represents 1 or 2; andthe structural unit (a02) is a structural unit represented by generalformula (a02-11) shown below:

wherein R⁰² represents a hydrogen atom, an alkyl group of 1 to 5 carbonatoms or a halogenated alkyl group of 1 to 5 carbon atoms; Wa⁰²represents an aromatic hydrocarbon group; part or all of the hydrogenatoms of the aromatic hydrocarbon group may be substituted with asubstituent other that a hydroxy group; and n02 represents 1 or
 2. 12.The resist composition according to claim 11, wherein the resincomponent (A1) is a, mixed resin of a polymeric compound (A11) having arepeating structure of the structural unit (a01) and the structural unit(a02) and a polymeric compound (A12) having a repeating structure of thestructural unit (a01) and the structural unit (a03).